2000 Dodge Neon Engine issues after valve job

RONKAREIVA

MEMBER
2000 DODGE NEON
4 CYL
FWD
AUTOMATIC
125,000 MILES

The car lost its timing belt while running damaging the valves. I got a valve job done on the car and I am having issues after changing the head gasket and putting the head back on. The car is running fine when throttled, however it is extremely loud. Also, the car will not idle properly, it is racing up and down at idle speed and the car sounds like it may be backfiring(only at low idle). I do cannot tell for sure if it is a backfire. I cannot see any leakage from the head and do not notice any coolant leakage internally or externally. Please help.

4 Replies

MMPRINCE4000

MECHANIC
8,549 POSTS

Perform a compression test on all cylinders, but it sounds like you have a bad valve (not closing completely). A compression test will tell you.

Bent valves will generally cause valve guide damage, were they replaced? It can also cause small cracks in the head.

As a general rule, if you lose a timing belt on an interference engine, you replace the head (if you are lucky) it can also cause piston/ring/cylinder wall damage.

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Tuesday, December 30th, 2008 AT 6:40 AM

RONKAREIVA

MEMBER
3 POSTS

The valves were replaced and a new head gasket was used. I do not know if the person who replaced the valves did a compression test or not and I do not have the tools to do so. Any explanation on the car sounding like a racecar? Or could that also be caused by a bad valve. Most of the noise seems to be coming out of the engine compartment.
Thanks

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Tuesday, December 30th, 2008 AT 10:26 AM

MMPRINCE4000

MECHANIC
8,549 POSTS

I would take it back and have a compression test performed, it will tell you if the head and valves are performing properly.

If compression is low on one or more cylinders, then the head will have to be repaired.

The noise could be a loose exhaust/intake gasket or a valve that is not closing, causing a backfire.

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Tuesday, December 30th, 2008 AT 10:34 PM

RONKAREIVA

MEMBER
3 POSTS

We found the cause of the noise, there was a cover plate that cover a smog or EGV that needed to be capped off. We forgot to tighten the bolts. We have checked the valves and made some adjustments hoping this will solve the issue. We will be putting the head back on with yet another head gasket. Will post again if this does not solve issue. Will donate more at that time if necessary.

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Wednesday, December 31st, 2008 AT 3:12 PM