Reader Question Last week my timing belt broke on my 2000 Nissan Frontier V6 2-Wheel drive truck. It was towed to my mechanic whom did not want to do the work. So, I towed it to a nearby shop that I called for a quote. The engine is an interference engine so I was aware that the valves might be bent resulting in major engine repair.
Except when idling, the engine runs fine, only when idling is there a serious vibration and the service engine soon light (yellow) is on. If a valve was bent, wouldn’t the engine run much rougher or make more noise? Could the new mechanic have not adjusted the timing correctly after installing the new timing belt?
That’s a good but tough question to answer. I have seen engines with “dead cylinders”, meaning the piston/cylinder had a problem and had low or no compression and they ran pretty ok but did not have the power they once had. You would not have guessed that one cylinder was dead and not contributing horsepower. I guess there could be a chance that there is internal damage, but I would probably want to rule out a few obvious things first before I came to a conclusion.
1. Is there a vacuum leak somewhere…listen for a hissing noise and look for a loose rubber vacuum hose or broken hose connector
2. Any other sensor wires that might be loose or just not connected all together
3. what is the computer code that is setting the engine light
4. did he run a compression test on the engine
Usually (but not always) on an interference engine multiple valves will be damaged not just one, so its pretty obvious that engine damage has occurred IF you can even get the engine running in the first place. Personally I have not changed the timing belt on one of these vehicles, so I can’t comment on how difficult it may or may not be. If the mechanic is not to keen on the idea of double checking his work and wants to blame internal damage, I think I would get a second opinion FIRST.
Reader follow up
Thank you for this reply, I will have a diagnostic and compression test done asap. By the way, is the diagnostic equipment used to generate a computer code from these tests, exclusively done by dealerships or is the equipment common place at most reputable mechanics?
Hi again Jeff
Most up to date repair shops should be able to read the computer codes on this vehicle. I would still visit the dealership though, you really really really don’t want a wrong diagnosis on this repair. I would hate to do a valve job thinking there was a bent valve and find out it was a silly vacuum leak that was misdiagnosed. It happens. At least get a diagnosis from them, then you can get anyone to do the repair.