Bent Valves, timing off?

ILuvCelicas · #1 04-26-2005, 06:42 PM

I was changing the timing belt on my 91 CRX Si with a stock D16A6. I tightened the pulley bolt without the car in gear or my foot on the brake and the belt skipped teeth on the cam gear but not the crank gear. So I realigned it based on the marks that were on there and the car still didn't start. We did compression tests on the the cylinders and they came up as 30, 30, 10, 15 PSI (or something pretty close to that) but the car wasn't warm like the tester recommends. We think I bent valves, but in every cylinder? It didn't turn too too much and it was only by hand. If the valves are bent, should I rebuild the head I have, get another A6 head from the junkyard, or get a Z6 head (time and money all considered)? Also, is it possible that the timing is off with the marks lined up? If so, how do I fix that? Thanks in advance for the replies.

Exempt · #2 04-26-2005, 10:16 PM

Did the belt brake on u originally? From the sounds of it, dosnt sound like u messed up on the install of the belt... Being off just a tooth or 2 shouldnt bend any valves...

ILuvCelicas · #3 04-26-2005, 11:29 PM

No, the belt didn't break, I was just replacing it because I had just bought the car. But when I was tightening the pulley bolt with the belt on, the belt slipped a few (not sure how many, could've been like ten or fifteen) teeth. I lined it back up based on the marks but my dad thinks that when I tightened up the bolt I could have bent the valves. I didn't think it was possible at that speed, but I can't really explain the compression or the not starting if the timing belt was put back on the original marks. Thanks for the reply.

travagliante · #4 04-27-2005, 12:10 AM

sorry cant help much. But as long as the tensioner iwas sorta tight and still connected to the block, there is no way that it could have slipped 10-15 teeth off. maybe a couple but not 10, id say take off the lower and upper cover and make sure the lines both line up(facing up)

Exempt · #5 04-27-2005, 01:16 AM

Yea man, I dont know what to say either... I dont think a bent valve would occur under those circumstances... But I suppose its possible... Id do like travagliante says and take the covers off and check the marks again... But even if it were off a tad, it would still start, it would just run rough... If it were off alot then yes, surely u can bend valves... But the only way is to check it... If its way off, thats the problem... Chances are u bent a valve while starting it... In whatever case, if u bent the valves, Id just swap for a Z6 head and do a mini-me...

EF You · #6 04-27-2005, 10:09 AM

you probably didnt bend valves. my belt snapped on my old d-series while i was driving, and it didnt bend any. before i knew what it was, i tried cranking it a buncha times, and it didnt bend anything.

i put a timing belt on a car once, and it started fine. then i shut it off, finished up under the hood, and tried to start it again and it wouldnt, the timing had jumped. i removed and reinstalled the belt and it ran fine after that.

what you need to do is make sure your block is at TDC, not only by the mark on the crank, but also by putting a long skinny object in the sparkplug hole on cylinder 1. as soon as the object stops rising out of the hole and wants to start travelling down, you are at TDC, then align accurately with the mark on the crank. you may have aligned it incorrectly originally.

after that, align the cam. theres 3 marks on the cam, two on opposite sides, which align with the top deck of the head, and one angled mark, which aligns with a mark on the side of the head. make sure they all line up. ive seen a few occasions where the diagonal line didnt line up perfectly, since its lining up with a mark on the plastic dust cover, and sometimes the dust cover isnt as true as it should be. but the other two marks are sure fire, they line up with the top deck of the head. just make sure the diagonal mark is close when you have the other two exact.

ILuvCelicas · #7 04-27-2005, 11:50 AM

I am an idiot. I did skip like 15 teeth, but I didn't turn the crankshaft pulley back that much. The belts and the marks lined up because the marks on the crankshaft cog were 180 degrees apart. So when I positioned the crankshaft at TDC using incucivic's advice, the cam gear was 90 degrees off. So the timing belt didn't slip, I just wasn't as thorough as I should've been. I'll reposition everything tonight and hope it runs. Anybody know the likelihood that I killed some valves with the crankshaft off 180 degrees? Thanks to everyone for their input.

Exempt · #8 04-27-2005, 12:05 PM

Quote:

Originally Posted by ILuvCelicas

I am an idiot. I did skip like 15 teeth, but I didn't turn the crankshaft pulley back that much. The belts and the marks lined up because the marks on the crankshaft cog were 180 degrees apart. So when I positioned the crankshaft at TDC using incucivic's advice, the cam gear was 90 degrees off. So the timing belt didn't slip, I just wasn't as thorough as I should've been. I'll reposition everything tonight and hope it runs. Anybody know the likelihood that I killed some valves with the crankshaft off 180 degrees? Thanks to everyone for their input.

Ew... 180 degrees off? Dats not good... Id say 50/50... But u may get lucky... Realign it tonight and try it out... And keep us posted...

ILuvCelicas · #9 04-28-2005, 12:27 PM

OK, I realigned it and it ran. Best moment ever. The head sounds pretty much like it did before. I did a valve adjustment but it's no quieter (could just be I did the adjustment like I did the timing belt). But now it seems like I have a lack of low end power. When we were lining up the timing belt it didn't line up exactly so we had to pick a way to turn the cam slightly. Maybe we just picked the wrong way. Would that cause that? Anyway, no real driveability problems. Weird idle, but it had that for the most part before. Thanks to everyone for their help.

turtlecrxsi · #10 04-28-2005, 01:20 PM

If you retarded the cam timing by accident, it may be the reason for loss of low end power... maybe.

EF You · #11 04-29-2005, 08:18 AM

told you it wouldnt bend valves. the only time i saw a d series bend valves was on a d16z6 with high compression pistons and a milled head, and it broke the timing belt in the middle of a race.

id say if the teeth didnt line up exactly, and you moved the cam or the crank a little to make it line up, that you probably retarded the timing a little. my advice is rather than tearing the whole thing down again, line the crank back up to TDC, take the top cover off the timing cover, see where your cam is at, and then just loosen the tensioner and move the belt. the tensioner can be accessed through a little rubber plug in the bottom timing cover.

when you put the belt on, did you start at the crank, pull it tight up to the cam, and then around the water pump and tensioner? because if you did it in any other order, you could have left just enough slack that it didnt line up tooth to tooth....

POST REPLY TO THIS THREAD