I was driving from nc to fl, in the last hour my timing slipped about 4 or 5 teeth on my intake cam (evo 8)(2003) due to a damaged timing belt. I re- timed it when I got it home did a compression test and the numbers were like 115-125-120-115. I did a hot compression test about a week prior to this and it was 175 across the board so I didn't bother to put oil in the cylinder. the outcome was quite obvious to me after the timing slip and low compression numbers that I had some bent valves. so I pulled the head and took it to a machine shop, they told me that NONE of the valves are bent... im a little confused, has anyone ever seen this bad of a slip and no damage to the head? I don't really see any damage to the pistons either, maybe a tiny scrape on number 3 cylinder where the valve relief is, but that's it, is this divine intervention? lol any input or opinions would be great I have S2s so I figured the large lift in those cams would theoretically do more damage on the valve slapping against a piston. im stumped

 

How positive are you that the timing slipped 4/5 teeth?

 

I put the crank at TDC and the ex. cam was lined up perfectly at TDC, the intake cam gear was about 5 teeth off from the mark, I put the intake cam back in time with everything and did the compression test, it even started with a very weird idle. then after I let it cool down again I pulled the head and got the odd news from the machine shop

 

I slipped 4 teeth because of the oil pump seizing up. I changed everything and it ran perfectly fine.

 

That's pretty bizarre. I mean in theory we both should have done damage. Unless I'm underestimating what 4 or 5 teeth is. Basically what i have gathered is one tooth is about 10° give or take. And I've also heard on some adjustable cam gear thread that going past 4-6° is playing with fire pretty much. Unless I am mistaken...any other input out there?

 

These can go quite a few teeth off without bending valves, and even more with just nicking them but not damaging them. I get a incorrectly times DSM about once a month or so because dipshiat independent shops and DIYs can't figure out how to make the damn marks parellel. I've seen 4-5 teeth many times with no damage.

 

Did the machine shop pull the valves and roll them? You lost some compression somewhere.

 

^^ this at least. you only have .040 of the valve to seat to seal around the valve. If you tweaked them--your done. Hard to see with just your eye

 

ok cool, that's definitely reassuring thanks!

yes they did, they grinded the sealing surface and all of the grind surface was straight, no choppy sounds when re-surfacing the valve seating area, just one smooth sound so they are good, i just basically had them clean everything up, hot tank/ sand blast, new Viton valve seals, check for wear on everything and put it back together. i have a cometic head gasket kit as well, im just waiting on getting the money to buy the stuff for doing the timing belt like the tensioner, etc... and time to put everything back together. at least this literally gave me a reason to do my arp head studs the right way! lol i was just gonna do it the 1x1 method until now lol anyone have any special tips/ tricks to doing a timing belt/ pump/ tensioner?

 

Once I had my timing belt changed and the guy that changed the belt somehow got it off and my mom had picked it up (who doesnt know whether my car is running bad or not) and drove it 40 miles home. I got my car back immediatly knew something was wrong wouldnt rev past 3k (safety feature I guess) and my starter burned out in the next 3 starts (compression was off) took it into a shop and my timing was off. I dont remember by how much honestly but none of my valves were bent and since then my car has ran fine no problems.

It might have been 9 degrees? idk I would have to find the old reciept he wrote it on there.