Timing belt mess....

[PS172]

Just messed my timing belt install, the tensioner was not tight enough, so it skipped some teeth on the belt, some valves bent, engine was being turned by hand, so no major piston damage suspected. The question is , can the heads be removed w/o taking the exhaust manifolds off, they seem quite imposible to dismantle with the engine on the car. First time this happened to me , done many timing belts in the past. If someone can give me insight on this will be greatly appreciated..

 

[Bravo]

The NSX experts will chime in, but from what I've read, you can pull your heads with the engine in, but it'll be MUCH easier to drop the subframe/Engine/Trans assembly.
Sorry

 

[PS172]

Already dismantle the intake manifold and the camshafts, but the front exhaust manifold looks tricky??? , will it came off together with the head if the 3 bolts at the downpipe connector are removed??? space between the firewall looks quite narrow... Anyway now that all the valves are closed it will be posible to perform a leakdown test to isolate which cylinder bank has bent valves,, if any , Iam really not sure as the rear exhaust camshaft got out of sync by about 45 degrees, but tappet adjustments were all out, was a stupid mistake did not tighten the tensioner after taking up the slack.

 

[PS172]

Well let me put it more simple, can the heads be removed with the factory exhaust manifolds attached, need to know as the manual is not clear about, and it will be easier to detach them outside the car, please if somebody has done it advice, thanks.

 

[Larry Bastanza]

How do you know you bent any valves?

 

[gt_nfr]

I 2nd Larry's question. I did the same thing during my install, I also skipped one tooth...but no bent valves. Cars been running great for the last two months.

 

[PS172]

Easily, already removed all the camshafts and did a a leakdown test with compressed air and there are big air leaks in the 2, 4, and 5th cylinders, if all the valves are closed there should be no leaks. Already only thing left to be removed is the vtec assembly for head bolt removal, and the exhaust manifolds. Can the heads be removed with the exhaust manifolds attached????, also there were several tooth skipped not one only. Is the front exhaust manifold the one is giving me headache.... I had worked on many midengines in the past, X1/9. fiero gt, a 328 gtb, but no longer have access to a lift to drop down the engine. Also Iam getting older, cannot get easily were I used too...

 

[Larry Bastanza]

You may get the front head off with the manifold, but not the rear. I have personally never done either removal "in the car" so my comment is not from experience in regard to the front, which is why I said "may".

BTW, had an engine recently came to me not running, intake cam 4 teeth off, no bent valves.

Regards,
LarryB

 

[junior40er]

Things like this is what scares me from doing my own tb change.

 

[PS172]

Ok, will try and post my results with the attempt to remove the heads and the manifolds, might be interesting, will try to document with photos....

 

[PS172]

Heads pulled with both manifolds attached w/o any problem, no bent valves. Found blown headgasket between cylinders 2 and 3. Will take head to machine shop for milling, and valve stem seals replacement, Mild rust spoting found on upper section of both cylinder, most likely headgasket was blown by previous owner some time ago. But the car did not smoke or overheated when driven.
Also found a repair bill for radiator hoses and coolant replacement dated a year ago. Otherwise the engine looked spotless inside no crud found. Should I be concerned about the rust spots???

 

[Larry Bastanza]

Heads pulled with both manifolds attached w/o any problem, no bent valves. Found blown headgasket between cylinders 2 and 3. Will take head to machine shop for milling, and valve stem seals replacement, Mild rust spoting found on upper section of both cylinder, most likely headgasket was blown by previous owner some time ago. But the car did not smoke or overheated when driven.
Also found a repair bill for radiator hoses and coolant replacement dated a year ago. Otherwise the engine looked spotless inside no crud found. Should I be concerned about the rust spots???

OK, I am confused. What about the three leaking cylinders from post #7? Do not get me wrong, I am happy to hear no belt valves, but that is a way different scenario then previously described. I would strongly recommend you find a good trusted machine shop, have the valves water tested, valve guides measured, and head shaved as required. Do not skimp on this at all. Payback is HIGH.

BTW, Did you remove the pipe on the rear manifold that is "U" shaped to get it out, or did you wrestle it out with that on the manifold?

Regards,
LarryB

 

[PS172]

Yep, you are right about the valves, they looked visually allright when tested at the machine shop with water they found 4 bent exhaust valves leaking, plus and unknown bonus, there was and old 10mm flange nut like the ones used in the valve cover studs loose inside the head crevices. The nut was all crushed and battered around, so most likely has been bouncing around the head for a long time. Strange I did no find any missing nuts, so most probably somebody loose it in a previous job and replaced with another. Was lucky to find no damage to the rockers or cams, if that nut became lodged between moving parts it would had been a real disaster.

The Camshaft position sensor was all melted, and front bank knock sensor disintegrated when disconnected.

About the heads they came with the cast iron manifolds out, I disconected them from the downpipe in the front, and from the rear manifold joint just after the o2 sensor before the U pipe, no trouble at all.

Cleaned all the rust with wd40 and a cotton towel but the dark spot remains on the cylinders, no pitting noted should I be concerned?, dont know how long the car was running with busted headgasket, since there was no smoke or overheat.... I had been with the car for 3 months.
So now will be a long wait for the parts to arrive, for the machine shop to work on the heads.

Will pull the oil pan to clean and check the bottom end, and change a slightly leaking pan gasket, the rest of the exhaust will be disassemble as headers and catback are going in...:biggrin:

 

[PS172]

After almost one month waiting for parts now the heads are back in the car the cams installed will be putting back the TB, and doing the valve lash adjustment, is it and involved, but doable procedure with the engine in the car, just tedious. BTW is very instructive getting to know how the VTEC works.

 

[PS172]

Timing belt installed, valve lash adjusted... every single o ring, hose, and oil cooler pipe replaced as it was quite rusty, as well all gaskets in the heads. Will really hate to do all that again. Will be installing headers tomorrow, with a Dali catback. Cats studs seized on the front one will need to grind the residual nuts that are badly rusted, and replace the studs.