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Blown head gasket

8K views 73 replies 14 participants last post by  Rollerolds 
#1 ·
I think the Trooper’s head gasket gave way. Pretty sure it didn’t overheat, though. Heard what sounded like an exhaust leak at freeway speeds and a distinct loss of power, pulled over and she idled super rough (almost died). Oil is lighter than when I last checked it but coolant isn’t foggy. Pretty sure I see wetness on either side of Cyl #4 (closest to firewall). Knew I’d have to do this at some point, but always annoying when you’re left stranded.
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#2 ·
First step will be a compression test when I have time.

Any gasket kits people recommend? I’ve seen advice to get a genuine Isuzu gasket but I can’t find it for sale anywhere. Any options are appreciated, don’t want to do this again.

Any preventative maintenance or replacements I should do while the head’s off?

Thanks
 
#4 ·
You can get an OE Isuzu head gasket from our resident Isuzu Guru Jerry Lemond in Dacula, GA. JLEMOD on this forum, you can message him. Or contact him at jlemond@bellsouth.net

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Drain your oil, if it is contaminated with coolant you don't want that mixture in there for long, coolant eats bearings.

Besides a compression check, do a pressure test on the cooling system, that may tell you something.

If you have to pull the head, easier to remove the hood then pull the head and intake out as a unit. You can undo the EGR pipe and unbolt the exhaust manifold; tie it to the side, out of the way.

If you want to remove the intake before pulling the head, about the only way to do that is to remove the upper plenum. Then you'll have access to the mounting hardware.

If the head is original and, especially if the casting # at the firewall end is low (i.e. #1 or #2), recommend getting a new head. By the time you have the head pressure-checked, surfaced (as required) and a valve job, you'll have a ton of $$$ into machine shop labor and material. New head is somewhere around $650 from Clearwater Cylinder Heads in Florida, a much better, more reliable option. New design and better materials drastically reduce the possibility of cracking and exhaust valve burning, which was a big problem with the earlier run of factory heads.

Very important to have a good head gasket in there and I wouldn't use anything but OE, as long as they're available. Fel-Pro would be the 2nd choice.

Anyway, check everything over carefully, maybe it's not a blown gasket. G'luck with the repairs.......ed
 
#5 ·
You can get an OE Isuzu head gasket from our resident Isuzu Guru Jerry Lemond in Dacula, GA. JLEMOD on this forum, you can message him. Or contact him at jlemond@bellsouth.net

Use Large Font in deference to Old Eyes.

Drain your oil, if it is contaminated with coolant you don't want that mixture in there for long, coolant eats bearings.

Besides a compression check, do a pressure test on the cooling system, that may tell you something.

If you have to pull the head, easier to remove the hood then pull the head and intake out as a unit. You can undo the EGR pipe and unbolt the exhaust manifold; tie it to the side, out of the way.

If you want to remove the intake before pulling the head, about the only way to do that is to remove the upper plenum. Then you'll have access to the mounting hardware.

If the head is original and, especially if the casting # at the firewall end is low (i.e. #1 or #2), recommend getting a new head. By the time you have the head pressure-checked, surfaced (as required) and a valve job, you'll have a ton of $$$ into machine shop labor and material. New head is somewhere around $650 from Clearwater Cylinder Heads in Florida, a much better, more reliable option. New design and better materials drastically reduce the possibility of cracking and exhaust valve burning, which was a big problem with the earlier run of factory heads.

Very important to have a good head gasket in there and I wouldn't use anything but OE, as long as they're available. Fel-Pro would be the 2nd choice.

Anyway, check everything over carefully, maybe it's not a blown gasket. G'luck with the repairs.......ed


I have done half a dozen head gaskets on those engines to include my own twice. Why twice you say? Bc I didnt listen the advice that ED and several other gave back in the day and didnt use a OEM head gasket. Have learned my lesson. Get in touch w Jerry if you need one, and take Eds advice on disassembly. If you have questions you can PM me personally and Ill give you my number and we can chat.
 
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#7 ·
Also did several using both fel-pro and an oem from Jerry. All turned out well, but if I do any in the future it will be an oem .You can see the quality of the oem when looking at it compared to others.
 
#8 ·
one mistake is using gasket tack. the gasket has to be able to float between the cast block and aluminum head. made that mistake ONCE....Fel Pro is good, OEM is best.
 
#12 ·
Can't they drill the EGR ports in the head? There might be an extra charge for that, but it would be worth it.

BTW did that cyl head refurbish estimate include a pressure check and examination for cracks? DO NOT reuse an Isuzu 4-cyl head unless it's pressure-checked. Unless you want to take the risk of dumping all the labor, time, and parts into a used head that may already be cracked or have issues sometime down the road. Been there. Done that. Don't recommend it.
 
#13 ·
Can't they drill the EGR ports in the head? There might be an extra charge for that, but it would be worth it.

BTW did that cyl head refurbish estimate include a pressure check and examination for cracks? DO NOT reuse an Isuzu 4-cyl head unless it's pressure-checked. Unless you want to take the risk of dumping all the labor, time, and parts into a used head that may already be cracked or have issues sometime down the road. Been there. Done that. Don't recommend it.
I'm not sure on drilling the ports but one could certainly ask. Ditto on the pressure check.
 
#14 ·
Good thoughts. Thanks. I’ll reach out to Clearwater. If that’s beyond their scope I’ll double check with the machine shop.
 
#15 · (Edited)
My first 2.3 clearwater head I bought was complete with cam. My second for my 89 2.6 was without the cam, The head comes with the cam caps. Just need to swap over the cam and rockers. Had no issues with mine, and it's running great.

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#16 ·
My second for my 89 2.6 was without the cam, The head comes with the cam caps. Just need to swap over the cam and rockers. Had no issues with mine, and it's running great.
Any issues with loose cam bearing fits or any other concerns moving an old cam into a new head? Sounds like Jerry's all out of cams at the moment.
 
#17 · (Edited)
I didn't have any, and don't really remember reading of any problems others have had ordering the head without the cam. I should have mentioned the rocker shafts and metal rocker retainers must also be swapped over to the new head.
along with the cam and rockers.
 
#18 ·
All good advice. Missing is: Make sure that block surface is PERFECTLY clean. Then check it with a straightedge front to back and across. After head installation, be sure you do the re-torque of the head bolts at 1,000 miles. Dennis
 
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#19 ·
Chase out the head bolt holes in the block with a 12mm x 1.50 bottoming tap then blow out with air, carb cleaner, etc. A razor-blade-type paint scraper makes a good scraper for the block surface.

There shouldn't be any issues with using the existing camshaft, long as the cam lobes and journals look good.

Delta Camshaft in Tacoma, WA offers a "272" grind which isn't too far off from the Jerry Cam. They can grind your cam if they don't have any in stock. Otherwise they'll ship one to you and you send back your good core cam.


Here's an old thread with my old RS, the new owner had some good comments on using the Delta cam:


Scroll down a ways for the comment from "Oregon RS".

Check the rocker shafts and rocker arms for wear. I had some severe wear on my old Spacecab 2.6 when I had a valve job done. Jerry Lemond saved me a lot of $$$ with a good used set of rocker arms & shafts. Pull the rocker shaft away from where it sits on the shaft and check the rocker shaft for scoring.

Check each rocker on an unworn area of the rocker shaft, for slop. Anything more than the slightest side-to-side free play is unacceptable and will likely lower your oil pressure. Replace as needed. Rockauto carries rocker arms but they ain't cheap! They also have the intake rocker shaft in stock, but you'll have to search around for the exhaust shaft if you should need a replacement.

HTH............ed
 
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#20 ·
Oh, I forgot to mention that if you use a performance cam in these heads, to correct the valve geometry you will likely need to install a set of lash caps. The lash cap fits on top of the valve stem and the extra thickness keeps the valve adjuster screw from contacting the valve stem at an excessive angle.

Fortunately the 8mm lash caps used in VW air-cooled applications are a perfect fit.

They're inexpensive and readily available:


 
#21 ·
Update:

Finally got around to pulling the plugs and getting a compression test done. Rear two cylinders @ 0, front two @ 130 psi. Exactly what I suspected. Plugs are pretty indicative of the problem as well.

Hoping to get the repair underway soon, but some things & questions:
  • I'm going to attempt to source an OEM or similar head gasket from Jerry. Second option will be a Fel-Pro.
  • I'm going to attempt to also source an OEM 180º thermostat from Jerry - if that doesn't pan out, any other preferred brands?
  • I'm going to attempt to get a Jerry cam from Jerry - and thanks for everyone's earlier comments re: heads, I'll make sure it's all done right.
  • I'm going to get a new radiator. Any preferred options? I was looking at a CSF 2-row from Rock Auto, thoughts?
  • I'm going to replace any and all suspicious looking hoses and vacuum lines.
  • I'm considering getting a new water pump while I have everything apart. Thoughts? Brand preference?
  • Any other things I should consider replacing while the head's off?
( In the photo of the spark plugs, left two are cyl 1 & 2 counting from the firewall, right two are #3 and 4 )
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#22 · (Edited)
Well, that's where the head gasket usually blows, it's the fire ring, between #3 and #4 at the thinnest point. My good buddy, long time ago, picked up an '88 SE as I recall, beautiful rig with a blown head gasket. He put on a Pro Topline head and aftermarket gasket that came with the head. Guess What, about 2000 mi later the gasket blew out! I related to him about aftermarket gasket issues, and he did a gasket R&R with OE part. Ran great after that with no problems.

For best success, I'd still recommend getting an OE gasket whether it's from Jerry or another ZuZu source. I'm pretty sure that using an OE gasket saved my bacon when my Spacecab lost a belt on the hiway and the water pump & alternator stopped turning. I was less than 10 miles from home, so I turned right around and went back. When I got there the coolant was just starting to bubble out into the overflow bottle, so that's really hot. Not a full-blown overheat, but close enough! After that I re-torqued the head and the rig ran flawlessly for years after. I have no doubt a lesser gasket would have blown. The ZuZu gaskets are just that much better.

Have had good luck with the Stant thermostats in my V6, but I see Rockauto is carrying Aisin 'stats which would be the OE part. Hard to go wrong with that, and a 180F 'stat is available for $8.02 plus shipping. Definitely not a part to scrimp on!

Yeah, if you can get the Jerry cam, that's the best bang for your bucks on the 4-cylinders. Pick up a set of EMPI VW lash caps on eBay for cheap, to correct valve geometry with the big cam.

Water pump-wise, Gates is a good brand and the pump for a 2.6 has a limited lifetime warranty. Better than the Beck/Arnley which is more $$$ and only has a 3-yr, 36,000 mile warranty.

Replace the camshaft oil seal, the rubber half-moon valve cover insert, the valve cover gasket, & holddown bolt grommets. A new intake gasket, of course. Inspect all the hard-to-access hoses off the intake manifold while it's apart, you won't regret that!

You might consider renewing the belt and belt tensioner while you're in there, and inspecting the oil pump. Sometimes you'll see a weepy seal, gasket, etc. Good time to fix those while it's apart.

Radiator, that CSF one at Rockauto looks OK. It's an Old School Brass & Copper, it'll be more than adequate for your engine. I'm running a 2-row metal rad in my 3.4 and have never had any cooling issues with it, even when towing at hiway speeds on a hot day.

All of the aftermarket rads come with a transmission cooler in the bottom, so all you need to do for a manual-trans car is to cap off the pipes for FME.

Sounds like a plan, eh! Good Luck with the repairs............ed
 
#23 ·
Progress. Looks like the crank pulley needs to come out for the timing belt?

The cam timing mark for TDC is ever so slightly off when the crank mark is at 0, like by less than half a tooth. Is this fine?
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#24 ·
One possibility, your harmonic balancer has delaminated. It's a 2-piece construct and the rubber bond can break with age, then the outer ring with the timing mark rotates around. So it's possible that it could be off a bit.

Also could be an indication of the head having been milled sometime in its past. This will change the belt timing slightly, too. The book recommends that if you can't align the marks perfectly, it's better to be a 1/2-tooth advanced than to be 1/2-tooth retarded. Advanced cam timing gives you more low-end torque while retarded cam timing increases the top end.

For best accuracy, when you get the harmonic balancer pulled there's an aluminum seal housing that bolts in around the crankshaft/front of the block; this housing has a timing mark cast into it. That mark is Top Dead Center perfect. So if there's any doubt about the harmonic balancer, before you remove the timing belt see how the cam sprocket aligns with the inner TDC mark. That'll tell you if the balancer is off.

A good trick to get the harmonic balancer bolt loose is to get a long breaker bar (1/2"-drive or larger) with the appropriate socket for the bolt, and with the breaker bar/socket on the bolt, place such that it's propped against the frame or other substantial metal on the driver's side. Preferably stick a short hunk 'o wood (2x4, whatever's handy) between the frame and the breaker bar.

Pull the fuel pump relay(s) so you're not injecting fuel when you do the next step: Clutch pedal to the floor or auto trans in Neutral/Park, foot on brake, manual trans in neutral, just "bump" the ignition to START. Don't leave it there. Just a bump is all you'll need and the torque of the starter will bust that bolt right loose. If it doesn't work, you'll have to pull the radiator and use an impact wrench.

For removing the balancer itself, you can rent a harmonic balancer puller kit at Autozone for free (full deposit on pickup, deposit returned when you bring back the tool). You may need to source some long metric bolts to screw into the puller holes on the balancer, get a good grade of bolt at Fastenal etc it the puller kit doesn't have them.

Attached you'll find a page out of a factory service manual, showing the timing belt alignment top and bottom.

Also a pic of the crankshaft area showing the belt alignment, with the mark on the seal cover. Zoom in on that pic and it very clearly shows the alignment of that timing mark with the crankshaft keyway at TDC #4 & #1.

Hope that helps!...........ed
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#27 ·
Current rad has a leak, what’s the reasoning behind avoiding a new rad? (New rad is already here and old rad is already out)
 
#28 ·
Oof reading this thread makes me somewhat ill Lol. CMF I rebuilt my 88 and replaced pretty much everything. I cheaped out on the head gasket at the very end. Needless to say just like Ed's example mine blew after about 2000 miles. Right between 2 & 3. Just like your scenario on the highway except I limped it home on 2 cylinders.

Hell I did not know OEM HG's were available. I used a Felpro this time & so far so good but now I'm worried. The quality of parts these days is not great sadly
 
#29 ·
... I cheaped out on the head gasket at the very end. Needless to say just like Ed's example mine blew after about 2000 miles. Right between 2 & 3. Just like your scenario on the highway except I limped it home on 2 cylinders.

Hell I did not know OEM HG's were available. I used a Felpro this time & so far so good but now I'm worried. The quality of parts these days is not great sadly
As far as I know, the Fel-Pro is fine all things considered. I trust them way more than other off brand gaskets. But I'm still hoping to get an OEM HG from Jerry, but no luck quite yet. Otherwise I'll use a Fel-Pro.
 
#30 ·
I used a Felpro HG, AC Delco water pump and a Motorad(Murray) 180 degree fail safe thermostat when I did mine and no issues.

I've got an old Modine radiator that must be over 15yo I've used with no issues. I'll try to get it repaired if/when its time comes.
 
#31 ·
Update:

Head is off, photos attached. HG clearly blown where we all expected it to. Bottom end looks good - I can even see the machining marks on the cylinder walls.

A couple random questions:
1. On the cam cover behind the cam sprocket, looks like there used to be some sort of gasket seemingly made out of foam? Does this need to be replaced? (Photo attached)
2. Does the check valve nipple come off of the valve cover? Is it press fit or screwed on? Should I leave it alone?

Anything look off from any photos? Thanks all
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#32 ·
The "check valve nipple" is your PCV valve. It's screwed into the valve cover. Remove it to test. Compressed air should easily pass through from the valve cover side. Blowing through it by mouth from other end, the air should pass through with difficulty. If in doubt, replace.
 
#34 ·
The head looks good. Glad it came back with a clean bill of health. Just a few things to ensure success:

-Check the head bolt sockets, if they look good and the threads are in good condition, you can reuse them. They are not torque-to-yield bolts.

-Chase out the head bolt holes in the block with a 12mm x 1.50mm bottoming tap. Blow the crud out with carb cleaner, etc or air source.

-Scrape block scrupulously clean with a razor-bladed type of scraper. Use a bit of WD or Marvel to lube, which helps scraping smoothly. You can suck all debris out of the top end with a vacuum. Run a crevice tool down in the cylinders to pick up anything that may have fallen between top of piston and cylinder. Go over the various passages in the block, too. Degrease mounting surfaces, head and block, before installation. Use no sealing compound of any type.

-I had good luck with ARP Ultra-Torque fastener assembly lube, makes for a smooth and accurate torquing of the head bolts. Apply to bolt threads and upper side of the washers where the bolt heads contact.


-When firing the engine for the first time, point the rig uphill or front end on ramps & "burp" the air out of the cooling system with the radiator cap removed. There are a number of products including Lisle brand ("Spill-Free" Funnel) that make the job a lot less messy. You don't want air pockets, this head already has enough "hot spots" manufactured in! Plus air in the system can cause poor coolant sensor function which can lead to a racing idle (running the engine faster to flow more air over the radiator because it "thinks" the engine is overheating).

BTW to answer a previous Q, that cork seal on the back of the timing cover is just a dust shield, you could replace it if you can find one, or just use a bit of gasket dressing on it. I don't recall doing anything special with mine, it's not a super-critical part other than the space it occupies.

HTH & Good Luck with the installation.........ed
 
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