2.6L Cylinder Head removal
(Return to Troopers.)
This is complied from my recent experience doing this head job doing it in minimal time with the least amount of work 'cause I'm lazy. This guide does not cover the changing of the timing belt or tensioner, however it's probably recommended that you do so, especially if those components have a significant number of miles on them. This guide does not require pulling the radiator or fan or power steering pump bracket either.
Note that the head and intake manifold will need be removed as a single unit, and possibly the exhaust manifold too. The intake will need to come off with the head because the battery tray prevents easy access to the intake (cannot get to intake manifold studs).
For reference, here's some links to very detailed photos that MarkB.NV has provided:
Head ==> http://markb.smugmug.com/Cars/Tooper-Head-job/5173951_M38Xd#172724447_nN9Uo
Motor ==> http://markb.smugmug.com/Cars/Trooper-Motor/10369579_K78ZS#944781908_yvVEG
Vacuum Lines ==> http://markb.smugmug.com/gallery/10168009_oP4hb#1142722088_hnpQq
Some additional info on 2.6L heads:
Head castings: Casting number for the cylinder head is located on the back side of the head - very large size number. Heads with a casting of 1 or 2 (mid 80's vintage) were prone to cracking whereas castings with 3 or 4 were much more reliable, and casting nos 5 & 6 very reliable.
Jerry Lemond (Isuzu Guru) says: 97 WAS THE LAST YEAR FOR THE 2.6, IN THE RODEO AND THE PASSPORT, NOW A LITTLE CAUTION , THERE ARE 2 DIFF 2.6 CYL HEADS IN USE, AND YOURS HAS WHAT IS COMMONLY CALLED THE HI COMPRESSION HEAD WHEN INSTALLED ON THE 92 AND EARLIER 2.6 ENGS, BE sure OF THE CYL HEAD YOU GET AND MAKE ABSOLUTLY CERTAIN THAT IT IS THE CORRECT HEAD ANY 94 AND LATER 2.6 HEAD WOULD BE THE CORRECT ONE AND SOME OF THE LATE 93 EVEN HAD THEM, NO 92 ENG HAD THIS HEAD, IF YOU USE THE OLDER HEAD ON YOUR (newer)ENG YOU WILL HAVE ABOUT 7.0 TO ONE COMP , JERRY
oldestisuzuist says: Sometime around '92 the 2.6 pistons were changed from the older shallow circular dished top to a deeper pie-shaped dish. To bring the compression back up the head chamber volume was decreased. Using this later head with earlier style pistons gives a compression boost similar to using a 2.3 head, & it's EFI with the larger valves. Seems like I read that they did away with the air pump with this mod- can anyone confirm- if so it might not be an option for you if it doesn't have air pump ports.
Cylinder Head REMOVAL instructions:
Edited from http://www.4x4wire.com/forums/showflat.php?Cat=&Board=UBB68&Number=683421&Forum=&Main=683421&=#Post683421, some things differ where I disagreed with their information.
First off, remove the air cleaner and intake crossover tube. Then, search the entire head for any ground cables or vacuum tubes that connect the to any portion of the unit that's going to be removed. Remove the battery as it'll be in the way later.
1. Remove throttle cable: remove 10mm retaining nut on stud, then remove the cable end from the throttle body shaft/bracket.
2. Remove intake tube. loosen the clamp at the throttle body and the one a few inches to the right.
3. Remove all hoses from the valve cover. one to the backside middle of the cover, one to the thermal valve on the thermostat housing, and the pcv hose going from the front left side of the cover to the intake. You can now remove the intake tube from the throttle body, and move it over to the right side of the bay.
4. Drain coolant. The drain plug for the radiator is on the right (passenger side on LHD models). [My note: Do NOT drain the oil]
5. Unhook upper radiator hose from thermostat housing.
6. Unhook the smaller coolant hose from the backside of the intake manifold.
7. Unhook the ground straps from the back left of the valve cover. 10mm bolt.
After you're sure that all of the vacuum tubes and ground cables are removed from the intake, you can now pull the coil wires and take the valve cover off.
8. Unbolt the 2 wiring connections from the coil (one is the noise suppressor (condenser)).
9. Unhook the vacuum lines from the round piece on the back left of the cover, or remove it from its clip.
10. Unbolt the 3 nuts holding the valve cover on. these are 10mm. remove valve cover.
11. Unhook the 2 gas lines on the passenger side on the intake manifold.
The above pic shows the fuel inlet line.
12. Unhook the 3 electrical connections going from the intake manifold to the passenger side fender.
13. Unhook electrical connector going to the distributor.
Note: I don't unhook this, I just leave it connected and will lay the distributor out of the way with it still connected.
14. Unbolt the grounds towards the front of the intake manifold. 10mm nut on a stud.
15. Remove radiator fan. 4 13mm bolts or 12mm nuts depending on fan style.
Note: I see no reason to remove the radiator fan so I skip this step.
16. OK, then it's time to pull off the top of the timing chain cover. It's just a little plastic cover in front of the head with four 10mm bolts attaching it.
I've added these next steps to ensure that cylinder #4 is at TDC of the compression stroke. You want to do this to ensure that the engine starts & runs properly.
16.1 Turn the engine over by hand until the timing mark on the cam pulley lines up with the little arrow on the top of the rear timing cover. Then you should take a paint marker and mark the timing belt and the pulley on the second tooth over from the timing mark. This will ensure that the belt goes back into its proper placement.
17. Loosen timing belt tensioner. 12mm lock bolt gotten to through access hole in the lower timing
cover.
18. Rotate the motor at the crank clockwise (24mm bolt) until you see the tensioner wheel move out to the right. Now tighten the tensioner. This little bit of rotation to loosen the tensioner wheel should not be enough to move the piston very much - it should still essentially be at #4 TDC and the cam gear and rear timing cover marks should still be pretty much lined up.
Note: Steps 17&18 are done to release tension on the timing belt to allow easier removal.
19. Remove the 14mm bolt holding the cam gear on. pull cam gear off cam, and remove the belt from it.
Once that pulley is removed it is imperative that you DON'T, DON'T, DON'T, move the crank or the camshaft if you just plan on replacing the head gasket, and nothing else. Because if you do move it, you will have to remove all the front pulleys, radiator, timing cover, ect. and you'll have to manually reset the timing marks again. If you plan on replacing the timing belt and such, do these operations prior to removing the valve cover. These steps are merely overlooked in this situation to save time and lots of headache if you're only needing a new headgasket.
19.1 Remove the distributor cap, label and remove the plug wires from the spark plugs.
19.2 Note the rotor position and distributor position at the hold down bolt! When you reinstall the distributor, you must put it back so that rotor and distributor is turned in exactly the same position for ignition to be timed properly! Here's a photo of how it should look:
Notice that the rotor is pointed in the 10:00 and 4:00 O'clock position, with the contact end at the 10:00 O'clock position if cylinders #1 and #4 are at TDC. If for some reason cylinders #2 and #3 are at TDC, then the contact end of the rotor will be at 4:00 O'clock instead.
19.3 Now remove the distributor hold down bolt and pull out the distributor from the head.
Note: if you can't pull the distributor out and it appears that something is still holding it down, there's an O-ring that will sometimes stick in there like you wouldn't believe, so you may need to pry the distributor out. Try wedging a screwdriver between the back plate and the distributor, and rotate the distributor back and forth as you're prying.
Also sometimes the bracket can move and the distributor hole won't line up and keep the distributor from coming out. Try loosening the one bolt below the distributor that holds it onto the head and see of that helps any.
Now it's time to pull out the power steering pump. It's something you can't get around because there is a long bolt (actually a stud) that runs through the inside of the power steering bracket and bolts to the head. You can see a long spacer between the bracket and the head that the bolt runs through. Make sure you find this spacer when the bolt is removed.
19.4 Remove these 2 fasteners shown in pic below to free up Power Steering Pump to allow you to move it out of the way.
20. Remove 2 14mm hex headed bolts holding the power steering pump to the bracket. Pulling it forward, you will have access to the top 8mm bolt that goes through the bracket into the head.
This is a stud from the factory (mislabeled as 12mm - I think the nut might be 12 or 13mm, but the stud is a 8mm), so double nut it to remove it (put 2 nuts on it and tighten them against each other as shown in the pic below).
Use an offset box end wrench and loosen the inner nut to remove the stud (shown in pic below).
After this, it's time to tackle the EGR pipe. It runs from the back side of the exhaust manifold, behind the engine and up into the rear of the intake.
The above pic shows the back of the head so you can see how the EGR pipe connects the exhaust manifold to the intake manifold and is bolted to the head.
You have a choice of removing the EGR pipe from either the exhaust manifold or intake manifold, or leaving it alone and pulling the entire intake/head/exhaust manifold together as a (heavy) unit.
You can try to free it up on the exhaust side and wrench the rusted thing off but that seldom happens without damaging the fitting somehow. You can also take a 22mm open end wrench and take it off from the intake side. There is almost no room to swing the wrench, but if you keep flipping the wrench over with each movement you'll eventually get it. But remember it's also clamped to the back of the head so you still need to get that clamp removed.
If you're successful, you can then unbolt the exhaust manifold from the head. If not, you have to go underneath and remove the nuts off the 3 exhaust studs. But be aware that these exhaust studs will probably snap off, requiring you to drill them out and retap the manifold. I had to drill out 2 studs and tap them (10mm). I then used bolts instead of studs.
21. Remove the 3 14mm nuts at the flange connection on the exhaust manifold. make sure the pipe is broken loose from its seal. you may or may not be able to get it completely clear of the studs. it will come off when remove the head easily as long as the seal is broken at the gasket.
22. Remove electrical connection at the o2 sensor. (if you're pulling the exhaust manifold with the head)
Now you can remove the last of the bits that still attach the head to other systems. There is one heater hose near the EGR fitting in the rear of the manifold (shown in one of the photos above). ALSO, if the truck is an automatic, there is a throttle kickdown cable that runs up through the intake manifold coming underneath from the transmission. Pull this off the throttle body, and pull it down through the intake making note of where it was snaked between different locations.
After that you can start breaking the head bolts loose. One at a time in the correct sequence.
23. This is a critical step to avoid warping the head. using a 10mm hex bit, begin loosening the head bolts. you want to only loosen them IN VERY SMALL INCREMENTS, 1/4 TURN OR LESS until they are all completely loose. then you may remove them as normal bolts. take your time, it can get tedious and some will likely be very stubborn to loosen.
After all of these are removed, gently tap the head with a rubber mallet to break the seal of the gasket. (dont hit anything critical though)
24. This is where an extra set of hands is very helpful. make sure you've retmoved everything in the steps above, and nothing it tangled/caught anywhere to obstruct removal. one person on the driver side holding the exhaust manifold, one person on the passenger side holding the intake manifold. slowly lift straight up, being aware of anything possibly left attached or catching on things. the intake, head, and exhaust manifold will come out as one assembly.
After you do this, here should be two alignment sleeves stuck either in the the bolt holes in the block or in the head. They go in one front and one rear head bolt hole, and line the head up when you put it back on. DO NOT LOSE THESE!! You WILL need these when replacing the head!
25. Clean the block and head using a scraper, a single edged razor blade works best. Go over the entire block very thoroughly several times and scrape all the crud and old gasket off, I assume you've done a head job on some other vehicle before so you know how to clean a head.
26. Lay a straight edge on the block, checking for warpage across each diagonal. Here are the specs courtesy of psguardian:
If it has been decked, the amount milled off should be stamped in one of the corners on the deck surface. Just take the decked amount out of your safety limits. For ex. If your head has been milled 0.2mm you only have another 0.2mm for correction, so if any of your measurements show 0.3mm on any of the 36 points (6points x 6lines) its asking you to measure your head is toast & will just eat head gaskets if you insist on using it anyway.
Distortion of lower face: (Head deck surface)
Make six measurements on the four sides and the diagonals. If the limit is exceeded, make necessary correction or replacement.
Factory Standard: 0.05mm(0.002") or less
Installable Limit: 0.2mm(0.0078")
Repairable Limit: 0.4mm(0.0157")
Distortion of manifold face: (Intake & exhaust)
Make measurement in manner similar to that for the cylinder head. If the limit is exceeded, make necessary correction
Factory Standard: 0.05mm(0.002") or less
Installable Limit: 0.4mm(0.0157")
Cylinder Body: (block deck surface)
Make six measurements on the four sides and the diagonals. If the limit is exceeded, make necessary correction or replacement.
Factory Standard: 0.05mm(0.002") or less
Installable Limit: 0.2mm(0.0078")
Repairable Limit: 0.4mm(0.0157")
Here's the head thickness specs:
Thinnest factory head - 3.661" / 92.989mm
Thickest factory head - 3.671" / 93.243mm
Minimum usable head - 3.642" / 92.506mm
Measured from Valve Cover landing lip to deck surface.
Felpro reports that their head gasket for this engine: Crushed thickness is 0.047 inch.
REINSTALLING THE HEAD:
Heater Hoses: You'll notice after removing the head how the heater hoses are routed behind the head. They attach to a 3-way junction block that is bolted via 2 bolts to the bellhousing. I personally found this very annoying and decided that this support wasn't at all necessary, and having this junction block bolted to the bellhousing really got in the way of removing those bellhousing bolts later if I ever needed to pull the engine or transmission. Also, if a hose ever needed replacing I decided it would be so much easier to be able to remove the whole thing rather than having to wrestle with those connections while the contraption was still bolted to the bellhousing. So I decided to just cut those mounting tabs off.
Heater hoses with original factory tabs.
Heater hoses with tabs cut off.
Heater hoses attached. Notice that cylinders #1 & #4 are at TDC.
1. Make sure you put the sleeves back in before setting the head onto the block. The head gasket needs NO sealant or silicone gasket maker. NO SEALANT OR COMPOUND ON THE HEAD, BLOCK, OR GASKET.
2. Head Bolts: 12mm 1.5 tap size needed to clean out bolt holes in block. Squatch says: The only bolts that I am aware of on the 1st gen Troopers that Isuzu says to replace are the bolts holding the flywheel to the crank. Head bolts are fine to reuse. Ed Mc. says: Neither 2.3 or 2.6 head bolts are Torque-to-Yield. Period. If the head bolt threads are in good condition, and the allen socket heads are not stripped out, you can clean the bolts and re-use.
Torque sequence
7 3 1 5 9
8 4 2 6 10
Start at 50 ft-lbs for 1st round, then 60, then 70, final torque 79 ft-lbs.
- NOTE: AMC head specify a final torque value of 72 ft-lbs.
3. Reinstalling the Power Steering bracket to head spacer
Remember that PS bracket stud with the spacer that we took out, allowing the spacer to just fall? Well now we have to get that spacer back in, which is a major PITA. First, I'd suggest replacing that stud with a 55mm long 8mm bolt. Why the factory put in a stud is beyond me.
Now, there are 2 ways to get that spacer back in. The correct way would be to do the following:
1. Remove P/S pump from mounting bracket, BUT LEAVE hoses connected.
2. Remove P/S belt and set side.
3. Loosen idler pulley to take tension off of A/C belt, then remove belt.
4. Loosen front mount bolts on A/C compressor. I used thin wall 14mm socket, 1/4" drive.
5. Remove lower rear mount bolt. I used a 14mm socket, 1/4" drive, with ratchet/extension and universal adapter.
6. Remove upper rear mount. I used 14mm end wrench to loosen it, then took it out by hand.
7. Pull compressor out of mounting bracket, moving out and forward. DO NOT remove freon hoses from compressor.
This should leave enough room to remove two lower mounting bolts on the P/S bracket, leaving plenty of room to install spacer and upper mount bolt.
Here's a pic of the 2 bolts holding the PS bracket to the block:
It has been suggested that removing the AC compressor is not necessary to get to these 2 PS bracket bolts, but I'm not convinced this is possible because these 2 bolts are below the curvature of the AC compressor and I don't see how a wrench or socket can get on them without removing the AC compressor. But I might be wrong, wouldn't be the first time.
So here's what I did instead since I was too lazy to remove the AC compressor and all that just to get that spacer in. The problem with getting that spacer squeezed in is that it's just too big (long) to fit, so I cut it in 2 with a hacksaw. Note I cut it AT AN ANGLE, and actually I should have cut it at more of an angle than this.
Here's the spacer being cut.
I was then able to put the 8mm bolt in, put the 1st half of the spacer in and thread the bolt through it. I then oriented this half spacer with the cut angle so that the longer side was on the bottom, and the short side on top. The allowed me to put the matching 2nd half in and push the 10mm bolt on through. Note this is why it's important to cut the spacer at an angle, and actually more of an angle than I did, otherwise you won't be able to get it in. Here's the final result in the pic below:
This may not be the ideal way to do it, but the spacer is in place well enough to allow the bolt to be tightened down to support the PS pump. Note that this photo has the bolt mislabeled as a 10mm bolt, it's actually 8mm.
4. Reinstalling the distributor:
You need to reinstall the distributor with the rotor oriented the same way as you took it out (rotor at 10:00 and 4:00 O'clock, contacts on 10:00 side). Refer to the photos above from the removal. One thing to watch out for - if for some reason you loosen the 2nd bolt on the distributor hold down clamp, shown in the pic below:
You have to make sure you position that hold down bracket back correctly so that the distributor inserts back into the head properly. I made the mistake of loosening that bolt (I thought the ground strap attached there - it doesn't.) THERE'S NO NEED TO LOOSEN THAT BOLT so if you haven't, don't touch it. If for some reason your distributor doesn't insert back into the head all the way, trust me, I'm speaking from experience that it's that bracket that has moved slightly and you'll need to loosen that bolt to move the bracket around.
5. Reinstalling the cam gear:
Reinstalling the cam gear would appear to be fairly simple but I ran into problems that I'll outline here. There is actually a cap that is between the cam and the cam gear. The cam has a "half moon" key, upon which the "cap" slides on. This "cap" must slide all the way on, deep enough so that about 1/16" or more of the cam sticks out beyond this "cap". This 1/16" ledge is important because the cam gear needs this ledge to sit and align on. So make SURE your cap slides all the way down on the cam and gives you this 1/16" ledge so that your cam gear sits firmly on the cam when you tighten it down (with that 14mm hex head bolt and large washer). I don't have a photo of this cap, otherwise I'd upload one here.
My problem was that my half moon key had a slight burr on it, which kept my "cap" from sliding all the way down on the cam. This resulted in my having maybe less than 1/32" of "ledge" that I needed, so when I bolted my cam gear on, it did not align correctly and was cocked a bit. I did not observe this, so when I buttoned everything up and fired up the engine, she ran for a few minutes and then just quit. Trying to start her, I noticed that it sounded funny, as if my cam timing was way off (she sounded like an air compressor). Well, after much investigation, I figured out what happened was that my cam gear, being not seated well and cocked, wobbled enough while running that the timing belt skipped a few teeth. I finally figured out that that burr in my half moon key was keeping my cap from being installed all the way down, resulting in all my problems. So - something to watch out for. Make sure that your cam gear is on properly!
Another hint - if the belt is fairly tight you won't be able to easily get the cam gear on. Loosen the belt tensioner (shown in one of these pics here), this will actually let the spring pull the tensioner even tighter at first - you can't help that. Put the cam gear into place onto the belt just dangling on the belt. Hopefully you marked the belt so you know exactly how to line up the cogs so they go into the right grooves on the gear. And hopefully the engine and cam are positioned so that the keyways are lined up perfectly so the gear is ready to pop on. If you don't think they're lined up perfectly, turn the crank or the cam (crank is easier to turn) and line them up so that the gear is all lined up and ready to pop on.
Now that the tensioner is loose, you can take a pry bar - stick it between the cam and the center hole in the gear and pry up against the belt - what you're doing is to stretch the belt (or rather, the belt tensioner) to get max stretch. Actually the tensioner is moving, the belt isn't really stretching. (See photo above - note that the belt is marked so I know which groove goes into the marked timing gear tooth.) Now tighten the tensioner hold down bolt and the tensioner should be locked with the belt stretched out as far as you could make it go. Now the cam gear should slide onto the cam. Do that, put the cam bolt in and tighten it down.
Now remember to loosen that tensioner hold down bolt again, allowing the tensioner to do its thing and tighten up the belt. Now retighten the tensioner hold down bolt and the belt tension is adjusted, and your cam gear is installed. Make sure the timing marks line up ok and that you're not a tooth off on the cam timing!
6. Vacuum lines reinstalled:
The remainder of the installation is basically the reverse of the removal. There are 2 vacuum lines underneath the intake that people seem to have problems figuring out, so courtesy of MarkB.NV here's a vacuum line diagram:
One line runs to the F-splitter which then goes to the two VSVs on the fender well (vacuum switching valves). This is represented in the diagram as the T-splitter.
The other line runs to the blue "thermal vacuum valve" on the manifold. Then from the thermal vacuum valve, up to the BPT (back pressure transducer) and on to the EGR valve.
7. AIR Pump:
The AIR pump is an emissions device that pumps fresh air into the exhaust to reduce oxides of nitrogen. Typically air is pumped into the 2nd stage of a 2 stage catalyst but in these trucks it's simply pumped into the exhaust manifold. Removing the AIR pump will have no negative effects on engine performance, so many folks choose to leave it off. If you choose to do so, you can either remove the entire AIR rail, or if it's rusted into place, you'll need to plug the end of that rail so that you don't have an exhaust leak. I've been told that the fitting on the end of that rail is a 1/2" pipe fitting, so a pipe cap will fit. You do need to cap off that end because you cannot simply rely on the check valve that is attached there, as the check valve relies on air from the pump to keep it cool, and will likely burn out without it, leaving you with an exhaust leak. It appears that the fresh air intake to that AIR pump is a separate compartment in the air filter box, so it appears that not having anything connected there is ok, as the engine will not ingest unfiltered air through this opening.
8. Change the engine oil:
Remember I said NOT to drain the engine oil out in the head removal steps? This is for 2 reasons. One, if the oil is still fairly fresh and no coolant or other debris went into the crankcase, there's probably no reason to change the oil. But if the oil did get contaminated or you just feel better changing it, it's better to do it after you finish the job so that any contaminants have a chance to get flushed out. If you'd drained the oil before doing the job and debris dropped in, you'd have no good way of getting it out before putting fresh oil in. I run the engine for about half a minute before draining the oil just to circulate it through the filter too, to give the filter a chance to catch any debris that might have dropped in since oil runs through the filter immediately after the pump.
9. Burping the cooling system:
You must 'burp' the cooling system to purge it of all air, once you get it running again. Otherwise you'll get hot spots inside the engine and this could lead to problems. Point the rig uphill and with the radiator cap removed, let it warm up until you see water circulating through the radiator. Rev the engine a few times and this'll help move any air around and out. Once the thermostat has opened up and water circulates, you're pretty well assured all is well with the cooling system. Top 'er off, fill the overflow, and you're Good to Go.
Note that the thermostat must have a "jiggle" valve that is installed facing up. This "jiggle" valve helps bleed off trapped air.
10. Re-torquing the head bolts: After the head has been heat cycled a few times, it needs to cool off and be re-torqued, or else the gasket will seat in and squish down from the heat, with the bolts still in the same position. It's suggested that this be done after a few hundred miles of driving.
