91 GT low on power after timing belt replaced - Toyota Nation Forum : Toyota Car and Truck Forums

rsmchi · 08-17-2009, 12:36 PM

A friend has a 91 Celica GT (135k on a 5sfe and automatic) that had the timing belt break on his way home from work. We replaced the belt, idler and tensioner pulleys and water pump. It started right up, but the engine seems to be down on power and has a stumble off of idle. On the test ride it struggles to get the car moving (needs lots of throttle) and starts to feel better about 3k and then upshifts hard and with the revs down it's back to not a lot of power. I've removed the top timing belt cover to verify the cam gear alignment (a PITA since you can't do it visually, so I used a nail to align the cam gear hole and the dimple in the head) and all seems to be OK there. A leakdown test gave about 18% loss consistently on all 4 cylinders, so I don't think there's any valve damage. Any ideas what to check next? TIA,

Rob

Pineapple · 08-17-2009, 02:06 PM

Check disturbutor timing.

TBayToyotaBoy · 08-19-2009, 09:24 AM

Don't worry about valve damage, it's a non-interference head. But also: when you had the cam gear aligned properly, are you sure you had the crank at top dead centre for the number one piston? If it was off, that would explain consistent compression loss across all four...

christine_lives! · 08-19-2009, 03:10 PM

Timing guns are your friend! Slap one on and start her up, you'll know if you're off with the belt. The idle tensioner is tricky. What likes to happen is when the slack is taken up in the belt, the slack side will cause it to skip a few teeth to even out the tension on the belt. From the crank pulley to the cam will be too taut and the opposite side won't have any tension in it until it slips to even itself out.

It took some playing with to get my belt to time right. I used a gun and kept the engine on a floor jack with the right side mount off and top cover open. You can start and run her using the battery to get the timing without an alternator. It took me 3 starts to correct the slippage. Hope this helps ya!

rsmchi · 08-21-2009, 09:43 AM

Thanks for the info. Finally got some time to work on it last night and christine_lives! hit the nail on the head. Pulled the top cover off again (#3) and found that it was still 1 tooth off. Loosened the tensioner and moved the cam gear ahead and as I was tensioning the belt watched the whole thing rotate back about a tooth. Arrgghh. Once I got it set correctly, the car is back to its normal self. Thanks!!!