Slipped Cam Belt

[alexmi16 0]

Hi Guys,

 

My 1.9 Gti decided not to start at some point during the very cold winter we just had. I neither had the funds nor the time to sort it out then. I have finally had a look at it and the cambelt has slipped a tooth or two, which explains the non start as there is fuel and spark. I was just after some advice...

 

How serious will the damage be, if any? Could i get away with getting a new belt and tensioner on there, get it all timed up properly and seeing if she will start? Or am I just getting my hopes up and wasting my time?

 

Thanks in advance,

 

Alex

[smithy 1]

I have recently bought a 1.9 8v that had broken belt it had not touched a valve at all.

 

If it has slipped a few teeth I would change belt kit and water pump I reckon it will be ok,but at end of day you have nothing to lose by trying.

[alexmi16 0]

thanks man, will give it a go and post the outcome.

[Tom Fenton 1,548]

You must a least remove the water pump to check. If the coolant had frozen this could be the reason for the slipped belt as the water pump would not turn.

[alexmi16 0]

thanks TF - I'm pretty certain that's what happened. I'll be trying new coolant pump, tensioner cam belt and plenty of crossed fingers.

[vern 0]

When thecambelt slipped on my 8V, I bent alot of the valves, and sheared the locating pin on the cam pulley, so worth checking, if only slipped couple of teeth should be ok. Mine would still run with it slipped miles out, it ran rough though and was really hard to turn over due to the bent valves.

[alexmi16 0]

i just had a quick look through the spark plug holes, there is a shiny silver round patch on the top of piston number 4. Is this almost certainly a result of contact with one of the valves?

[Tom Fenton 1,548]

Certainly doesn't sound too promising. Two options are either assume the worst and off with its head. Or otherwise re time it and then do a compression test which will tell you if you have bent valves without removing the head.

[alexmi16 0]

cheers - just putting a spare belt on it now, and will do a compression test.

[alexmi16 0]

Right, so I got the old cam belt off. It's completely shredded all the teeth have been taken clean off. Yet it had only slipped by two or three teeth:

 

Shredded cam belt

 

I put a spare belt on and timed it all up. Did a compression test and it all looked a bit worrying as the readings were very low. But, she started up first time! PHEW!!!

 

Let her warm up for a moment and now getting around 170psi on each cylinder...what should I be expecting to see?

 

Thanks for all the help guys!

 

Alex

Edited June 5, 2011 by alexmi16

[Paul_13 212 1 Cars]

F*ck me looking at the state of that belt, i'm really surprised it's started!

 

No tapping etc?

[smithy 1]

I would say 170 across all 4 is about right,if it had clobbered valves it would be considerably lower.

The low compression when cold was probably as a result of being stood a while.

 

Good job it froze up I reckon as that belt is shot and could have gone at speed causing lots of damage.

[jackherer 543]

170psi on all four pots is a good healthy 8v. That is incredibly lucky really.

[Henry Yorke 269 3 Cars]

8'vs usually are more forgiving than 16Vs as the valves will touch the piston face on so less likely to bend. I did similar to Vern on my 307 HDI and sheared the woodruff key on the pulley. New belt, pulley, pump and tensioners and all was fine again and runs like a dream.