LUVTruck.com

OK, if you've read my post over in the 4X4 section, you know I have a '90 Trooper 4X4, 2.6L 5 speed. Its got a miss in the engine at idle, but get it up past 1500 RPM & it runs fine. I was told by the previous owner that it was taken to a shop & diagnosed w/ a "dead cylinder" and wasn't worth the value of the truck to fix.

Some of y'all suggested it may be a vacuum leak. Well, this evening I spent a little time under the hood looking for leaks- no such luck. All the vacuum lines seem fine, & I did the old "starting fluid" trick while it was running.

In the morning when I first fire it up, I hear a mechanical tapping noise that sounds like its in the top end. Usually goes away for the most part after it warms up.

I did a little trick I learned from reading over at PlanetIsuzoo & I believe I have the "good" casting of the head- #4. It doesn't lose water or burn oil, no water in the oil either. Will a cracked head on these things neccesarily leak water?

What I'm asking is where should I look next to diagnose this problem so I can fix it? Are these motors bad about cams or lifters going bad? Dropped valves? I'm not used to these overhead cam motors- will pulling the valve cover tell me anything obvious? Help me Obi Wan Kenobi, you're my only hope............

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'46 Studebaker truck "project"
'90 Trooper 4X4, 2.6L 5 spd

You need to have the valves adjusted every 10-15,000miles, that is more than likely the tick your hearing. With the head, a blown head could mean anything, it really depends on how it blows, the head on my parent's '88 blew recently and it wasn't lossing water or oil, and there wasn't the tell tale milkshake on the dip stick, same thing happend to the 1.8 in my Luv, kinda weird. But yeah get the valves adjusted ASAP, and keep an eye on the cooling system and the 2.6 should give you miles of trouble free service.

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'80 Luv 4x4, 3" BL, 1.5" SL, 32/36, 2.25" exhaust...and fuzzy dice.
'95 Toyota 4Runner Limited 5-Speed.

I didn't go back thru your previous post but i was wondering if you've pulled a compression check yet? This could confirm the dead cylinder theory.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

Nope, haven't done a comp check yet- I need to do that tomorrow. I'll post up the results when I get 'em.

I do remember now that the guy told me the truck wouldn't pass smog. He was told the dead cyl was pumping out too much unburned fuel to get the OK. Mentioning the comp test jarred my memory on that (no smog test where I live).

If I can figure out a good excuse for not doing a comp check yet, I'll let y'all know.......

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'46 Studebaker truck "project"
'90 Trooper 4X4, 2.6L 5 spd

Do the old plug wire test. Pull the #1 plug wire. If the engine slows down/misses, then that cylinder is not dead. Continue thru the other 3. If one of the plug wires doesn't make a difference, that cylinder is dead.

I recommend pulling the wire at the distributer. Once the wire is pulled, the wire isn't hot and there's less chance of you getting snapped. Trust me, this is the voice of experience.

Ever notice that experience is something you get just after you need it?

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You went there in that?!?!

i have my luv on a 88 trooper frame and it has the 2.6 5spd too i had a bad miss in it too and i had a warped head and a bad fuel pump test the compresion and then check the fuel presure it might just be a fuel regulater too.

OK, did the spark plug wire test & the comp test:
#4 is deader than a door nail.

1,2, & 3 all have 120 or so, & 4 registers nothing at all.
Pull a wire on 1,2,3 and idle gets rougher. 4 has no effect.

Will pulling the valve cover show me anything obvious, or will it take pulling the head before I know whats happening?

Thanx for all the help so far, guys.

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'46 Studebaker truck "project"
'90 Trooper 4X4, 2.6L 5 spd

Could be a few things. The head gasket could blow to the outside or in such a way that oil/water don't mix. The valves may be badly in need of adjustment. You could have a burnt exhaust valve. Could have a hole in the piston or obliterated rings. I think I put those in approximate order of how likely I think they'd be.

Compression on the other three is a bit low too, which could be good (valve adjustment) or bad (worn rings). I'd start by pulling the valve cover. Look for obvious mechanical damage, but I'd doubt you'll see much. Adjust the valves and note how far off they are, especially #4. You put #1 at TDC and do half of them, then turn the crank around one turn so that #4 is at TDC and do the other half. The specs should be on a sticker on the hood. If they are way off, that could get it.

Beyond that, you are looking at pulling the head to really find out more. Usually a cracked head bleeds water into the cylinder. You would have steam out the tailpipe and the plug on that cylinder would look like it had be cleaned. Its more common to see a crack on 2 or 3 though around the exhaust valve seats. That doesn't mean its not possible though to have a crack on #4. My Troop cracked in #1 and #3.

Hopefully you don't have the experience I just had. #1 lost all compression, and when I took the head off, I could not find a single thing wrong that could cause it. Valves are perfect, piston is still solid, and the rings appear ok. All I can see is the the pistons have a lot of slop, but that is on all 4 holes. I like puzzles, but I hate things with no answer

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

If you take the #4 plug out and roll the motor over to the compression stroke so that both the valves should be closed then take a air hose and put in the plug hole and pump air in the cylender if the air comes out the carb the intake valve is bad or needs adjusted if the air comes out the exhaust the exhaust valve is bad or needs adjusted if the air is coming out the dipstick the headgasket is bad or the rings are shot if the radiator fluid is bubling the head gasket is bad.


just my 2 cents

the bottom end of these Isuzu 4abngers is vary tough. Someone probly never adjusted the valves and it killed one on the #4. Thats what i would think. But youll know either way if you pull the head, and youll have to do that sonner or later anyway...

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1980 LUV 4x4, going under re-construction...

The bottom end is really stout, so odds are good the problem with #4 is in the head. About all you can do is adjust the valves and recheck compression if it still doesn't run right. Beyond that you are looking to pull the head to find or fix whatever it is.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

I'm still around- just don't post much.

I messed w/ the Trooper yesterday. I've put 10K miles on it since April w/ the dead cylinder. Fuel mileage is horrible, power is nonexistent, & idling is out of the question........ but for some reason I've put up w/ it.

I pulled the valve cover. No obvious problems jumped out at me. I went ahead & did a valve adjustment. They were off, but not drastically so. Some were a little tight.

When I restarted the Troop after adjusting the valves, the motor was set at TDC on #4 compression stroke. Cranked the motor & " KAPOW"- major backfire. But other than that, it ran better than it ever had. It idled, I drove it & it had decent power. But it was still "not quite right".

Parked it & did a compression check- #4 now had about 25 pounds of compression, whereas before it was completely dead. It would leak down over the course of a few minutes, though.

I decided to do the tips that Luv Junky offered, & did the air hose check w/ the motor at TDC #4. Nothing obvious. Radiator didn't bubble, no air seemed to come out of the dipstick, exhaust, or intake.

Put it back together, restarted it at #4 TDC, & once again- "KAPOW"... major backfire, then it ran.

But..... I was back to square one. #4 is dead again, it won't idle, & it has no power.

Any ideas?? Thoughts on why it backfires at #4 TDC, or why it had some compression until I did the air hose check? Could the cam be flat? Thanx.

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'46 Studebaker truck "project"
'90 Trooper 4X4, 2.6L 5 spd

Need to do the leakdown test again with higher air pressure in the cyl (put #4 at the bottom of the compression stroke) - use some sort of device to listen at different spots around #4 while it's pressurized and see if you can hear the air moving - around a valve, past a ring, etc. If you use like 150-200 psi in the cyl it should hiss enough to hear it.

After that it's either pull the head or use a boroscope to look insid the chamber. Although it sounds like the entire motor could use a refresh.

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1978 shortbed fleetside, th350, Fireball 231 Even Fire V6, Edelbrock 500CFM Performer with Edelbrock intake. Workin' Truck.

Found my problem:





The #4 exhaust valve has physical damage, obviously. The piston top is fine, though, & I see no other problems.

Any idea what happened?

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'46 Studebaker truck "project"
'90 Trooper 4X4, 2.6L 5 spd

That is a burnt/cracked valve, which could be caused by poor adjustment, a big chunk of carbon getting stuck in it, a bad exhaust leak at that cylinder, or poor quality metal in the valve, etc.

I'd just get another one and replace it or replace the head with a better used one, but I personally don't think you should replace the head with a new one or rebuild the head completely, unless you are planning to do a complete rebuild. That would most likely cause too much pressure on the old piston rings and result in blow-by and leave you with a engine that would be a smoker.

I've personally replaced plenty of bad valves with decent used ones pulled from another junk head, and had engines run fine for a long time...but I'm a notorious cheapskate...lol

gotta check the valve seat too... if it was all burnt up, then a new valve wont do ya much good
Checking the valve guides would be handy as well.

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Most likely the cause was lack of valve adjustment, just from what I've seen & know about the Trooper.

I'm thinking just a simple "go through" inspection of the valves/seats & replacing the bad #4 exh one will be the route I take.

I'm down a vehicle w/ the Trooper torn apart. I like driving my F600 winch truck, but driving it like a pick-up truck will get old soon, I fear.

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'46 Studebaker truck "project"
'90 Trooper 4X4, 2.6L 5 spd

Good point.

Usually when I run into something like this, if I've got good compression in all of the other cylinders, if it's nor smoking when it first starts up untill the engine gets warm (which is a dead give-away that you have some bad valve guides), and the bad valve's seat is OK and is not tore up, then I just replace the valve and put in a better guide with it.

I guess I just follow the old "If it ain't broke - don't fix it" rule...but it hasn't failed me or my wallet so far.

But what do I know...I'm so old I just read Playboy for the articles.....lol

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80 Luv with 88 trooper running gear 2.6 5sp 4x4

sorrry this is the first time is have used the quote button.........

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80 Luv with 88 trooper running gear 2.6 5sp 4x4