So i was driving and the timing belt broke in my 02 ls montero with a 3.5 engine.

It did not make any horrible noises however it did have smoke coming out from the side of the engine near the oil add cap.

I had it towed home and now it wont start and makes the horrible timing belt broken starting noise.

I guess i was wondering since its a interference engine......... is it toast ?

I really like this montero its one of the best rigs i have ever owned looks/feels/driving however not mechanical.

Is there any easy way to check for damage or do i have to take the entire engine apart down to the heads.

Thank you all for your input/advice/help.

JP

 

Best way to check for valve/piston damage is to do a compression check. Need to have a new timing belt on for this this to be meaningful.


Another less definitive test is to poke a borescope down the spark plug holes and visually look at each piston top. Depending on if you can do yourself the cameras are very cheap now (~$60) which may be a good starting point.


jim

 

Agree with Benckj. Doing a compression test will tell you if you bent any of the valves (you will not have compression if that is the case). Looking through the bore camera will tell you if the valves hit pistons, but that's about it. First of all do not attempt to start the engine until you install new timing belt. Otherwise what ever problem you may have - you are making it worse.
BTW, did you confirm a broken timing belt or you suspect that it is the case?

 

suspected belt not diagnosed. engine turn over sounds like the broken timing belt noise.
Harbor frieght has one of the cameras for 65 dollars would get one but funds are all gone from buying the car.

So open the top and do a compression test to find out?

this is so horrible why would they make an engine that would completely ruin itself if the belt breaks!!!!

the car took all my cash i dont have anymore to repair the engine!

 

There are numerous engines which will cause internal damage if belt breaks. Its a clearance issue between valves and piston and trade off with performance and efficientcy (compression ratio). This is why the manufacture has recommended maintenance routines under their schedule so that if adhered to break downs do not occur.


If you don't know if its the belt first job is to remove the cover and have a look to see what's wrong.


jim

 

That is the essence of the "interference" engine. Under normal operation valves open further than the top most movement of the piston but not when piston is at the top of travel. However, if timing belt is broken or not installed correctly, valves and pistons will come in contact (interfere) with each other. Most of the modern engines are interference types. This is done for reasons of efficiency and performance because you can get better air flow in and out of the cylinders with this design.

At this point do not do anything that involves turning over the engine. In fact, disconnect the battery cable, so that no one else turns it over. If the timing belt is truly broken, turning the engine over only makes things worse. First thing to do is to confirm or disprove that your timing belt broke. To do this, take off the timing belt covers (plastic covers on front of each bank on the engine). This will expose the cam gears and the timing belt. If the belt is not there (broken) you have to examine the cylinders for damage before deciding on how to proceed further. It might be very difficult to get the belt back on and time the engine if cams moved in relation to the crankshaft, but I'm sure there is a procedure for that. Examine you timing belt first first, then move forward once you know the situation.

 

Well i have yet to open it up and find out the extent of the damage.

My dad wants me to keep it no matter what. He said we could open it up and see how bad it is and either get it redone or get a new engine for it.
He wants a father/son project... probably to get some time away from my mother LOL.

Quick question.

If it cant be redone or is to much to do so and it comes down to swapping the engine can it be swapped with a 3.8 instead of another 3.5, or would that require to much modifying?
And is there any huge differences in the 3.5 vs 3.8?

thanks guys

JP

 

Had another quick question guys.

If the wrecking yard near me have a 3.5 out of a montero sport would that work?? or do the sports have a different version/attachments/hook ups than the regular montero?

thanks all

 

Was able to tear into it for the first time since it happened.
The timing belt did not break!!!
I was able to rotate it all by hand and checked the belt while doing so it was in good looking condition.

So I pulled the plugs/wires/ to get to
I took some pictures would like to know your guys opinions if its damaged.
When i pulled the plugs plug#2 and #4 were completely oil soaked!


Thanks

JP

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That is a great news. The oil soaked spark plugs - is there oil on the threads and on top of spark plugs, or are they fouled at the tip? Oil on top is from leaky spark plug seals (round rubber things on your photos). They get hard overtime and loose their sealing ability letting some oil seep through. On the other hand, if you are have burnt up oil on the tips or the spark plugs (in the combustion chamber), then you are dealing with some other issues. Two possibilities for that - worn valve guides, worn piston rings. To determine which one you are dealing with you need to run compression and a leak down test on all cylinders. Then you can compare values for the two cylinders you are concerned about with the remaining ones and determine which issues is most likely to be responsible.