Was coming to a stoplight, clutch engaged but no throttle,pushed in the clutch and this happened...



this is with the engine at TDC according to crank and timing cover marks. as you can see the intake cam is around 120 degrees off. The engine made sort of a popping noise when it happened and shut off, it turned over even like this, but of course never fired. I lined everything back up, and checked as best I could for any damage, couldn't detect any, haven't tried starting it back up yet. Just wondering if anybody here has any idea why this would or more importantly how could this happen. just put this engine in not a month ago, it's a b20 vtec with b16 head, stock valves but does have dual valvesprings. stock cams. haven't beat on it at all, only hit vtec like once. has a gates blue timing belt.

 

The timing belt probably jumped a tooth or a couple of teeth from being to loose. I dont really go by the manual when tightening them. It really doesnt let you make them tight enough.

 

Timing belt tension, [tensioner] most likely, possibly the wrong belt.

You will need to pull the head and inspect the valves, seats, piston tops and combustion chamber for damage.

If there is no damage, [like bent valve stems] consider yourself really lucky, immediately go out an by a lottery ticket, Honda engines are "interference" engines, when valve timing goes out, valve contact with pistons is the result, 99.99% of the time there will be damage, but like I said, you could be a lucky .01%er. 94

 

Yeah probably going to pull the head off this weekend and check it out, and get a new tensioner, hopefully this won't happen again.

 

Holy **** dont pull the head. Just do a compression test first and if it doesnt look like good results then pull the head. You guys must really love working on your cars. I wish I had that much desire.

 

I would use a oem timing belt next time...

 

 

After I had my timing belt replaced it jumped a tooth because it was too loose. Luckily it didn't ruin anything. I had this happen as I was starting the car so maybe thats why I was lucky, not sure.

 

I know this may seem like a dumb question but have you checked to see if your cam gear slipped at the adjustment?

If not then the best way to check your timing belt tension is to twist it and it shouldn't go no farther or no less than 90 degrees

 

just pull the head like what was said earlier...you could have luck out


i dont know if it is me or something but i seem to see a lot of timing belt threads (slipping jumpping teeth back tensioner)

 

Why? because alot of people cheap out and dont replace parts or dont do things right.

 

Why pull the head if he don't have to? That's a new head gasket he has 2 buy and the labor to do it. Normal procedure is but it back on timing and see if it got compression

 

A compression test will only show compression and if you do not have the time, money or tools then you may get away with just a compression test, however it would not show minor damage like "nicks/gouges" on the piston or valve and they can produce hot spots leading to more severe damage.

Spend a little time and money now or possibly spend a lot of time and money later.

As mentioned by mouab18c1, " because alot of people cheap out and dont replace parts or dont do things right" is just too true. 94

 

Yea timing belt, water pump tensioner and oil pump should all be changed with theses cars if you haven't done it already. Its like the heart of the engine, anything goes in there and your hurtin

 

Its a full 180deg. Cam gears allow 1-5 degree changes. Wonder if you sheared off the Key that holds the cam gear in place onto the camshaft.

 

Well, decided to go ahead and crank it, figuring if it did screw something up when it happened a crank up wouldn't make much more work for me, as it would have to come apart anyways. however I DID line it back up to TDC, took out all the plugs to inspect for damage, turned it over by hand several times, and unplugged the distributor at first. with no evidence of any damage done, turned it over and it did fine, no scary noises or anything. so plugged up the dizzy and tried it again, fired right up. I literally can't believe it didn't do any damage. I think that I will replace the belt with an oem one and the tensioner with a new one, this engine has less than 2k miles on it since being built (by a reputable builder) so the oil and water pumps are good. might go back to stock cam gears as well, even though they didn't slip at least I won't have to worry about that happening either.