Timing belt 1 tooth off - could this be my problem Topic is solved

Post by **Clemens** » 22 Nov 2018, 04:10

On my 95 T5M Wagon I´ve had a bucking issue at part throttle ever since I got it a year and a half ago.
The issue is that when I get on and off the gas it bucks, is sometimes a bit rough when trying to hold constant rpms in the 2-3000 rpm range, but feels super smooth under under boost.

So far I replaced or swapped in known good parts from my 96 R:

- Volvo Turbo plugs, gapped .28
- Dizzy and rotor (Bosch)
- Bougicord wires from 2016
- new throttle position sensor
- MAF sensor from the 96R (might be the original one, but the R runs really nice)
- cleaned PCV
- inspected all vacum hoses and sprayed them with brake cleaner. seem to be good
- sprayed intake manifold with brake cleaner. gasket seems good
- replaced the timing belt and tensioner and the pulleys. I locked the cams to the old position.

I get nice boost, no CEL on.

A Volvo mechanic I asked the other day said to double check the timing marks. And it looks like one is a tooth off.
Before throwing more money at parts: Could the timing being off cause theses bucking issues?

I guess yes, but what do I know?

Post by **misha** » 22 Nov 2018, 07:44

Yes it can....timing is the most important for engine to run properly.
When you re-set timing,remove negative battery cable for 15min in order to reset fuel trims....again.

Post by **Clemens** » 22 Nov 2018, 14:40

Mkay... nothing like wrenching in the freezing cold ...

I guess I can get away with temoving just the tensioner and pulley, I guess.

Post by **misha** » 22 Nov 2018, 15:30

If it's hydraulic tensioner...it's the only thing you actually need to remove.

Post by **Clemens** » 04 Dec 2018, 01:23

Now that I am about to tackle the job. I aligned the crank on it´s mark and the exhaust valve looks to be quite right but the intake looks off by about a tooth.
The red marks align, but they might have been from a previous TB job done wrong, I just mistook them for the red factory marks when replacing the TB this summer.

Should I try to set the exhaust one tooth back or is this what it should be?

: Timing belt off?

Post by **misha** » 04 Dec 2018, 05:34

Allign exhaust and intake with grooves on a plastic cover.
From the picture it looks that both are a bit off....but it could be a bad angle the picture was taken.

Intake a little back and exhaust a bit more back....check the crank..put the belt...re-check.

Post by **Clemens** » 04 Dec 2018, 08:00

I aligned the crankpulley again with my worklight and took another photo. This actually looks quite right to me.

So off to another round of guessing what causes the car to buck, because the timng belt can be crossed off the list, I´d say.

Post by **Ozark Lee** » 04 Dec 2018, 09:20

Looks spot on.

I have had two of them that were a full tooth off on both intake and exhaust when I went to do the first timing belt change after I bought them. It isn't as uncommon as you might think. The cars ran OK even with the timing off but ran better with it correct.

...Lee

Post by **misha** » 04 Dec 2018, 09:28

Don't forget to reset fuel trims after timing belt re-check by disconnecting neg.batt.cable.