rough idle after 2.5 sohc timing belt broke and replaced

[jimrichard]

The timning belt broke on our 1999 Forester 2.5 SOHC EJ25. Replaced all idlers tensioner water pump and belt. Car cranks slowly and then idles very rough, then stalls after warming up. Any ideas ? Heads and valves move smmothly and pistons are OK.

[Bad Brian]

sounds like the belt was put on wrong, and your timing is off a tooth or 2.

Edited April 20, 2009 by Bad Brian

[Hondasucks]

The 2.5 SOHC *IS* an interference motor, however it takes more than a few teeth off on the belt to bend valves (Usually only happens if the valves stick fully open when the belt breaks) so chances are that is not the case. There is a notch in one of the teeth of the sensor ring that's on the crank pulley -- This lines up with the center (dotted) line on the timing belt, and the two solid lines on the belt each line up with a line on the face of the cam pulley. Also, when you put the belt on, you should be able to read the words on the belt, if you put it on backwards it will not line up correctly and it will not run right! There is a good article in the End Wrench on how to replace the timing belt.

[jimrichard]

Read the words if facing the engine, correct ?

[davebugs]

Yea - when you're looking over the radiator.

[rguyver]

bent valves for sure ! they bend almost all the time when the belt brakes . but you may be lucky . do a compression test if its low then they are bent .

[nipper]

re check the timing marks on the sprockets, dont go by the belt. Even the best techs get the timing wrong on occasion.

 

If you have a vac gauge use that to tell if you have any bent valves. My feeling is that the timing is off.

 

nipper

[jimrichard]

If timing is off and I do a compression test wil it not be messed up ? How do I ensure a good test ?

[johnceggleston]

If timing is off and I do a compression test wil it not be messed up ? How do I ensure a good test ?

 

the only way to get a good test is for the timing to be correct and all valves and rings in good working order. if the compression is good then you need to look somewhere else.

 

if the timing is off, the test will show one or both sides with bad compression. if and when you recheck the timing marks on the crank and cams, take some pics and post them.

 

the most common cause of problems after a t-belt replacement is caused by using the wrong marks on the crank and cam sprockets. with a broken belt it's usually bent valves.

 

the test will show which head/cam has a problem, maybe both, and then take it apart to double check the timing marks. if the timing is correct, it has to be bent valves.

Edited April 23, 2009 by johnceggleston

[nipper]

Yup. Most the time a compression test will show really wierd numbers if the teeth are off. Either you will have very high numbers, very low numbers or one head high one low. It really is a good way to tell if the belt is off, as usually the two banks dont match if they are.

 

 

nipper

[jimrichard]

Yanked the heads and yep, bent valves. Will put the replacement heads on next week.

[davebugs]

Don't forget to have the new heads checked. Or at the absolute minumum check them yourself for warpage.