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1999 Isuzu Trooper - interference or non-interfence engine?

11K views 16 replies 10 participants last post by  Serapium 
#1 ·
It appears that my timing belt has broken and I'm worried that it could have caused many other problems since the car won't run. Can anyone definitively tell me if my 1999 Isuzu Trooper 3.5L V6 has an interference or non-interference engine? If it's an interference engine, what does that mean? Will I need to replace the entire engine? I was driving at about 50mph when my car stalled and it hasn't started since. Thanks.
 
#4 ·
All 3.2 and 3.5's are NON-interference motors. Just slap a new timing belt WITH tensioner and water pump in that bad boy and enjoy :)
 
#6 ·
Then I would not go there for the repair as he is NOT familiar with these trucks. Any Isuzu built 3.2 or 3.5 is a non-interference motor. The earlier motors that were made by GM i.e 2.8(?), 3.1, and 3.4's were all interference and were in the 1st generation Troopers only (and maybe 1 or 2 years of Rodeo's).

You do not have an interference motor. I just did a lot of searching to confirm, and came up with the same results :)
 
#7 ·
Sorry....but Firestone is NOT the place I would take my truck for anything other then tires, suspension maybe...engine work...no way.

Your mechanic there is telling you interference because when you look in the All Data books, it DOES say these engines are interference.

However, when my belt slipped, broke actually, on my 3.2L, I put all new timing belt parts into it, including waterpump and it started right back up....that was 3yrs ago, still runs like a champ.

When you say your truck hasn't restarted since the belt broke, HAS the belt been replaced and then restarted? Obviously it's not going to restart with a broken belt.
 
#8 ·
Mediamonkey is correct. You have a non interference engine provided its the original Isuzu engine and not from something else.

Your Firestone mechanic is not properly informed or is planning to charge you for a bunch of work you don't need. (Firestone shops are good for doing that and several have been sued in Florida when caught). Also, if you had them instal a new belt, it may not be starting because the Firestone guy didn't put the new belt in properly. There is a trick to getting it right.
 
#9 ·
Thanks guys. We haven't replaced the timing belt. The mechanic is a family friend, he looked it up in the computer at work and came up with the interference motor. He'll be doing the work for me on the side. I'm going to take your word for it though and pray that once we replace the timing belt, tensioner, water pump and the serpentine belt all will be good. Unfortunately, I can't afford to take it to an Isuzu dealer so that will be my last resort. I really appreciate all the helpful information you all have given me though.
 
#11 ·
newtotrooper said:
My Firestone mechanic just called back to say it's an interfence engine. I'm so confused.
The timing belt vendors seem to have it wrong. My 3.2 was listed as an interference engine too. After doing lots of research,I became convinced they were wrong and bought the truck. After a new timing belt and tensioner, she runs smooth as new. Those mistakes are a great way to get a cheap truck. The info from the vendors is really all the mechanics can go on as there are thousands of kinds of vehicles out there so all they can do is repeat what they read in the catalog. Still,I agree with the previous poster,take it to someone who knows Isuzu engines better.
 
#12 ·
johnnie59 said:
Mediamonkey is correct. You have a non interference engine provided its the original Isuzu engine and not from something else.

Your Firestone mechanic is not properly informed or is planning to charge you for a bunch of work you don't need. (Firestone shops are good for doing that and several have been sued in Florida when caught). Also, if you had them instal a new belt, it may not be starting because the Firestone guy didn't put the new belt in properly. There is a trick to getting it right.
Yea,mine was sold to me like that. The guy who tried to fix it screwed up the job. He was not a real mechanic BTW.... well,I would say some of those chain shops guys are not real mechanics either,but thats another story. This guy though didn't know ANYTHING,he just thought he could replace the "tensioner" which he was told went bad,and it would work. Turns out the tensioner PULLEY had paint marks on it from the wrecking yard. The valve timing of course was off so it didnt start. A new timing belt,installed right fixed that and it started right up,but made an aweful racket. The hydraulic tensioner of course was the bad part. Once that was replaced it runs like a brand new engine.
 
#13 ·
newtotrooper said:
Thanks guys. We haven't replaced the timing belt. The mechanic is a family friend, he looked it up in the computer at work and came up with the interference motor. He'll be doing the work for me on the side. I'm going to take your word for it though and pray that once we replace the timing belt, tensioner, water pump and the serpentine belt all will be good. Unfortunately, I can't afford to take it to an Isuzu dealer so that will be my last resort. I really appreciate all the helpful information you all have given me though.
Did the belt actually break,or start skipping and get chewed up. If its the latter,it may be that your tensioner is the part that went bad. Considering that I went down to the wrecking yard,found one with rear end damage that looked to be in good shape with a real clean engine,and took the tensioner out of it,and THAT tensioner was bad too I would say there is a real good chance the tensioner is bad. On mine, the original one could be depressed with your finger,the one from the wrecking yard could not,but still chattered like heck when it was put in. I then did what I should have done to begin with. I got a brand new one. My local Honda dealer price matched an online Acura parts place and sold me the tensioner for about 70 dollars,and they had it in stock,I just told them I was ordering for the same year Honda Passport. (You can get them cheaper than that I think from other vendors)

At the least,I would suggest replaceing the tensioner. I understand the rationale in replacing oil pumps,water pumps,bearings etc while your in there,but that can lead to a lot of money when your on a budget. My guess is though,if your tensioner is not bad,then its not bad yet. From what I have seen and read,if its not already bad,it WILL go bad,its just a matter of when,then your going to have to tear it all apart again.

EDIT: Im not a convert on changing the water pump while your in there. I got mine all ready to go and guess what,the water pump leaked. Had to tear it all apart again.
 
#14 ·
Others have already advised that Firestone may not have been the best place to take it. Good advice but like for me (in OKC) I have no idea where I could take mine where they would have a clue.

So don't feel bad about the choice but also know the shop is incorrect on the interference issue.

Based on that I would expect the next call from Firestone to be advising you the truck only runs on 3 cylinders. Would expect they will say this is because of bent valves because they don't know any better - when the cause is they do not know how to properly time the cams.

If/when the call comes look on here for the posts by DeerMagnet where he links to the Isuzu factory videos of how to set the timing.
 
#15 ·
Wow! Great thread! Tells me just what I needed to know, assuming it is my timing belt that broke. I was driving down the interstate 80 miles an hour and suddenly lost all power. I shut the motor off immediately, shifted into neutral and coasted to a stop. When I got out there was white smoke pouring out from under the hood. Does this sound like a timing belt symptom? The vehicle currently does not run, but it does have spark and it does have fuel. A guy that looked at it led me to believe it was the timing belt, but I've never heard of a timing belt causing smoke under the hood.
 
#16 ·
If an idler pulley for the t belt seized, it could cause it to smoke and then break. Was the smoke a pungent burnt rubber smell?
 
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