1994 Isuzu Trooper valvetrain question

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1994 Isuzu Trooper valvetrain question

Postby GetAWavestorm » Mon Mar 29, 2021 4:20 pm

the trooper has 150,000 miles and uses the SOHC 3.2L V6. manual trans, 4WD.

It's got a loud tick coming from the valve cover. I found a service bulletin that recommended cleaning varnish off of the hydraulic lifters. So I went to check for play in the rocker arms and found that both banks had rocker arms with play. Issue was worse on driver side. bot banks had play in a number of intake and exhaust arms.

I replaced ALL of the hydraulic lifters with new ones. The tick is still there. I have not had the time to take off the valve cover, but its an identical noise, so i assume the lifters were not the problem?

I dont have the exact numbers for oil pressure. But based on the dash gauge, it was within spec per the chilton manual

I definitely just threw a part at a problem and would like to not do that again :/

Any advice on where to start? I am gonna link a folder with some photos I took of the components

https://imgur.com/a/8IDmwXv
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Re: 1994 Isuzu Trooper valvetrain question

Postby GetAWavestorm » Mon Mar 29, 2021 4:24 pm

I am thinking that my next step is to check the lifters for clearance and see if they got filled up with oil? I saw someone had an issue not getting pressure on the top end because of a stuck relief valve
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Re: 1994 Isuzu Trooper valvetrain question

Postby Ed Mc. » Mon Mar 29, 2021 6:44 pm

How's your oil pressure? Another common issue with the early SOHC valvetrain is wear on the rocker shafts and rocker arms themselves.

Excessive clearances up there leads to lower oil pressure and ticking. So it might be time to inspect the rocker shafts/arms for wear.

Any discernible slop of a rocker arm on the rocker shaft is likely a problem.

Here's an old thread about the problem:

https://forum.planetisuzoo.com/viewtopic.php?t=13189

And some Good Words in this thread from our resident Isuzu Meister, Jerry Lemond:

https://www.planetisuzoo.com/viewtopic.php?t=134307

eBay has a selection of parts for these, and Amazon (among others) carries some parts, too:

https://www.ebay.com/sch/i.html?_from=R ... acat=33624

https://www.amazon.com/dp/B00TM143KQ

https://www.amazon.com/DNJ-ERAS350-1992 ... B00TLGDV28

https://www.amazon.com/DNJ-Engine-Compo ... B00TM145K4

Partgeek exhaust rocker: https://www.partsgeek.com/catalog/1996/ ... r_arm.html

Or contact our resident Isuzu-Meister Parts Guru, Jerry Lemond. He may have something for you:

[email protected] or username " JLEMOND " on this forum.

HTH..........ed
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !

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Re: 1994 Isuzu Trooper valvetrain question

Postby GetAWavestorm » Mon Mar 29, 2021 10:17 pm

Thanks for the links.

Do you happen to know of any photos of excessively worn rocker arms?

no matter what my next step is to take it apart again
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Re: 1994 Isuzu Trooper valvetrain question

Postby Ed Mc. » Mon Mar 29, 2021 10:34 pm

GetAWavestorm wrote:Thanks for the links.

Do you happen to know of any photos of excessively worn rocker arms?

no matter what my next step is to take it apart again


The wear on the i.d. of the rocker arms wouldn't be as obvious, you'd probably have to measure them with a bore gauge/micrometer.

The wear on the rocker shafts, where the rocker arms contact the shafts, will Most Definitely be obvious. If there are deep grooves/scoring in the shaft, or a wear ridge that you can catch with your fingernail, too much.

If you do end up pulling one of the rocker shafts, you can move each rocker arm aside, to an unworn area of the shaft. Compare any "slop" each rocker arm has where it's riding on the rocker shaft, to what you get on an unworn part of the shaft. It may be an eye-opener! :shock:

I'm sure there are service limits for the rocker arm i.d. & rocker shaft o.d., but the "eyeball gauge" can be quite effective to tell if you have enough wear to cause a low-oil-pressure problem.

The intake rocker arms are fairly inexpensive, whereas the exhaust rockers sure ain't! Ah, well, beats car payments! :mrgreen:

Maybe Jerry will have some good deals for ya. He fixed me up when I was doing my old 2.6 Spacecab, it had a very badly worn valve train.
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !
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Re: 1994 Isuzu Trooper valvetrain question

Postby GetAWavestorm » Mon Mar 29, 2021 10:37 pm

Ed Mc. wrote:
GetAWavestorm wrote:Thanks for the links.

Do you happen to know of any photos of excessively worn rocker arms?

no matter what my next step is to take it apart again


The wear on the i.d. of the rocker arms wouldn't be as obvious, you'd probably have to measure them with a bore gauge/micrometer.

The wear on the rocker shafts, where the rocker arms contact the shafts, will Most Definitely be obvious. If there are deep grooves/scoring in the shaft, or a wear ridge that you can catch with your fingernail, too much.

If you do end up pulling one of the rocker shafts, you can move each rocker arm aside, to an unworn area of the shaft. Compare any "slop" each rocker arm has where it's riding on the rocker shaft, to what you get on an unworn part of the shaft. It may be an eye-opener! :shock:

I'm sure there are service limits for the rocker arm i.d. & rocker shaft o.d., but the "eyeball gauge" can be quite effective to tell if you have enough wear to cause a low-oil-pressure problem.

The intake rocker arms are fairly inexpensive, whereas the exhaust rockers sure ain't! Ah, well, beats car payments! :mrgreen:

Maybe Jerry will have some good deals for ya. He fixed me up when I was doing my old 2.6 Spacecab, it had a very badly worn valve train.



thanks. nice tip. ill prolly get some junkyard parts. do one bank and see how it works. wasn't too much work the first time
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Re: 1994 Isuzu Trooper valvetrain question

Postby GetAWavestorm » Tue Apr 06, 2021 5:37 pm

Update:

Upper rocker arm shafts were badly worn for the intermediary exhaust rocker arms. The exhaust valves that correspond to this wear show pitting where lifter makes contact - but its not that bad. Photos are driver side but passenger side is similar.
https://imgur.com/a/JKSYBrK

About half of the intake valves have putting where lifter contacts. Photo is of worst one.
https://imgur.com/a/aZKnO50
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Re: 1994 Isuzu Trooper valvetrain question

Postby Ed Mc. » Tue Apr 06, 2021 9:22 pm

WHOA! :shock: I guess there's no question about the wear, is there! That's Really, Really bad.

Surprising it had enough oil pressure to keep running, with that bad of wear. Are you replacing the rocker arms as well? Because they're gonna be worn in a similar fashion.

Looks like you're renewing the valves, too. Good deal, the HLA's will have nice clean surfaces to slide against. There's not a ton of friction between the tip of the HLA and valve stem, so if the badly worn rocker arms and shafts were replaced, there most likely would be minimal noise or tapping. The 2 surfaces would tend to polish themselves out at the point of contact, and the HLA's would take up any wear, within reason.

I'm assuming you already pulled the heads, though, with a pic of an valve just sitting on the bench.

All nice, new parts should make for a very happy valvetrain with little to no noise, and better oil pressure to boot.

Keep up the good work!..........ed
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !

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Re: 1994 Isuzu Trooper valvetrain question

Postby GetAWavestorm » Tue Apr 06, 2021 9:38 pm

Ed Mc. wrote:WHOA! :shock: I guess there's no question about the wear, is there! That's Really, Really bad.

Surprising it had enough oil pressure to keep running, with that bad of wear. Are you replacing the rocker arms as well? Because they're gonna be worn in a similar fashion.

Looks like you're renewing the valves, too. Good deal, the HLA's will have nice clean surfaces to slide against. There's not a ton of friction between the tip of the HLA and valve stem, so if the badly worn rocker arms and shafts were replaced, there most likely would be minimal noise or tapping. The 2 surfaces would tend to polish themselves out at the point of contact, and the HLA's would take up any wear, within reason.

I'm assuming you already pulled the heads, though, with a pic of an valve just sitting on the bench.

All nice, new parts should make for a very happy valvetrain with little to no noise, and better oil pressure to boot.

Keep up the good work!..........ed


Ya, she burns some oil so I went to replace the valve seals anyway.

One thing I am curious about - a good number of the intake valves have pitting similar to the photo, though that one is the worst and its corresponding lifter has pitting as well. Before I pulled everything I wrote down which rocker arms had a little play. At that point I wasn't able to tell which part was causing the play. The pitted valves are the same ones with play. Lets use the pitted valve in the photo as an example. How can I tell what I should replace?

I am going to replace that valve itself and the lifter has been replaced. I am worried that whatever caused it will not be fixed? Was it bad oiling due to low pressure? The intake rocker arm for that valve seemed perfectly fine and I am already replacing the upper rocker arm shaft.

The intake rocker arm is pretty expensive is all. Thanks so much
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Re: 1994 Isuzu Trooper valvetrain question

Postby Ed Mc. » Tue Apr 06, 2021 9:48 pm

The wear on the valve stem is from the excessive clearances brought about by low oil pressure, brought about by the extreme wear of the rocker shafts/arms. Any of them "ticking" would be the ones showing some wear. Sometimes it's possible to have the ends of the valve stem resurfaced smooth. But you'd have to look at the specs for that.

Obviously there's a limit to the amount of slack that an HLA will take-up. But I'd imagine the amount of material removed off the valve stem by a machine/polish/etc would only be in the thousandths to clean it up.

A good auto machine shop could tell you that, and how much they'd charge per valve to clean 'em up.

BTW new intake/exhaust valves are pretty cheap at Rockauto.com
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !

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Re: 1994 Isuzu Trooper valvetrain question

Postby GetAWavestorm » Tue Apr 06, 2021 9:50 pm

Ed Mc. wrote:The wear on the valve stem is from the excessive clearances brought about by low oil pressure, brought about by the extreme wear of the rocker shafts/arms. Any of them "ticking" would be the ones showing some wear. Sometimes it's possible to have the ends of the valve stem resurfaced smooth. But you'd have to look at the specs for that.

Obviously there's a limit to the amount of slack that an HLA will take-up. But I'd imagine the amount of material removed off the valve stem by a machine/polish/etc would only be in the thousandths to clean it up.

A good auto machine shop could tell you that, and how much they'd charge per valve to clean 'em up.

BTW new intake/exhaust valves are pretty cheap at Rockauto.com


Ya I ordered new valves on rock auto. Just wanted to make sure the issue w them was the oil pressure
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Re: 1994 Isuzu Trooper valvetrain question

Postby GetAWavestorm » Sat Apr 10, 2021 8:16 pm

Update:

As I posted earlier, most of the visual valvetrain damage was on the driver side upper rocker assemblies. When I was replacing the valve seals on the passenger head, I notices that the oil gallery was completely or almost completely blocked by sludge. Looks like the block side is fine, but the head had about an inch of oil sludge. Pretty surprised nothing seemed too worn on this head. I assume oil was still able to get by. There wasn't much ticking or slop on this head
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