'91 GTP 3.4 Timing

[jrodz]

Can somebody please tell me in a difficulty scale from 1-10, how hard it is the set the timing on '91 3.4 GTP? Also about how long would it take?

[richtazz]

The 91 3.4L DOHC is distributorless, so there is no provision for setting the timing, it is all done electronically through the ECM. If you mean replacing a timing belt, on a scale of 1-10, 1 being easy and 10 being cuss inducing, I'd rate it an 8.5.

[jrodz]

Originally Posted by richtazz

The 91 3.4L DOHC is distributorless, so there is no provision for setting the timing, it is all done electronically through the ECM. If you mean replacing a timing belt, on a scale of 1-10, 1 being easy and 10 being cuss inducing, I'd rate it an 8.5.

On the contrary my friend, the #1 cylinder at this very moment is at TDC of compresion stroke and the marks on the camshaft do not align or meet. It is clear that the camshaft timing is off.

[richtazz]

From the way you described it, it sounded like you were trying to set the timing, not re-align the cam sprockets. A need to re-align the cam sprockets means the timing belt has skipped, necessitating replacing it. Hopefully, you didn't smack a valve, as the 3.4 DOHC is an interference engine. The proceedure is quite involved, so unless you are quite mechanically inclined, I'd suggest taking it somewhere.

[auxbar]

richtazz, I thought the same thing about the 3.4 DOHC being interference. But then I found this document that seems to say different.

http://www.familycar.com/CarCare/GatesFrame.htm


The 3.4's prior to 1996 might not be toasted if the belt breaks, but why take the chance? I changed mine at 100K, and I was overdue.

[richtazz]

The 3.4 DOHC engine uses the same short skirt piston as the 3.1, which over time get loose in the cylinder bore. The pistons will start to rock back and forth, causing the piston slap noise these engines are known for. This rocking motion causes the valve clearance tolerance to decrease from new, increasing the probablilty of a valve hitting the piston. I would err on the side of caution and do the timing belt as per manufacturers suggested interval, as the machine shop we had here where I work did a lot of 3.4 DOHC with bent valves after a timing belt jumped/broke.