friend might have blown motor... - Honda Prelude Forum

CrazieLude · 09-10-2003, 01:52 PM

my friend was going from 3rd gear @ 8000 rpm's to 4th and hit 2nd instead. the car surges at idle, wont idle for more than 10 sec w/o throttle, the valve train is really loud and we were wonder what the problem could be. Also, his spark plugs and exhaust valves are white. It sounds like its missing and popping really bad.

T

He has a 92 Si w/ JDM H22, the motor only has 39,8xx miles on it.

Dukespeed · 09-10-2003, 02:16 PM

From what usually happens when that occurs (miss shift) is bent valves. I would advise to yank the cylinder head yourself and save some dough that way check the valves I would say its a safe bet that some if not all the valves are shot. Once you get the head off (its not hard if you have a Helms) take it to a machine shop to put in the new valve unless you feel confident do it yourself. But from your description this would be my first guess without hearing/seeing it.

matt

CrazieLude · 09-10-2003, 02:18 PM

he is in the process of pulling the head off now. He cut the timing belt (dont know why) so the car isn't going anywhere soon. once he gets the head off, what should we look for any pix?

T

Dukespeed · 09-10-2003, 02:30 PM

I actually just did this thats why i know a little about it and yeah my pics should still be around let me look. But you wanna check how the valves are seating. Also once he gets the cams out of the way you can see if there is ALOT of play on the top of the valve. My t-belt lost ten teeth, not broke so after seeing my valves I did not bend any of them (super Lucky). I will go get my pics if they help at all

http://www.imagestation.com/picture/...7/fbf56a8b.jpg

Other than that I don't know what else the others will help. But check to see the valve is seating OK. Other than that its off to the machine shop. If mine were bent i was gonna go that route.
good luck and let us know how it goes and if you guys get stuck holla

CrazieLude · 09-10-2003, 02:32 PM

they will. thanx man.

T

CrazieLude · 09-11-2003, 04:01 PM

well we got the head off late wednesday night. manifolds off. everything is off pretty much. looked at the head a litle. and at first i was pissed cuz i thought i pulled the head for no reason. but now that i see it. im a little worried. valves are almost all white. obviously the combustion chamber the exhaust valves are black. but in the actual ports and everything. everything is white in there. on top of that. there looks to be small cracks on the valves and valve stems.

looked at the valves a little more. and they don't all seem to "sit" in the same place. some sit farther down in the head. than some of the others. not by much. but enough to feel with my hand pretty damn well.

spark plugs came out whitish brown. so a little on the lean side.

the tops of the pistsons are reallllllly black. obviously from combustion. but i didn't think they would be that black after just shy of 40k.

I'm just lookin for idea's right now. anyone have any idea?

btw. this is brian. theresa's friend.

Dukespeed · 09-12-2003, 06:21 AM

The tops of the pistons are normally going to be black. That is just from the combustion leaving behind the carbon. I know I too thought that was wierd but I had never ripped any cylinder heads off before. I also inquired about cleaning them. Don't bother it is perfectly OK to have it and its going to continue. If I were you it sounds like there some questions about what you are seeing. I would look to find a GOOD machine shop and get with a GOOD machinist and go through the head. You guys saved yourself alot of money tearing it apart now do yourself a favor and have the pros check it out. The intake manifold bolts are fun arn't they. I ended up taking the IM out with the cylinder head? worked out ok little heavier than just the head but oh well. The cracks in the valves cannot be good have them looked at or if you feel up to it do them yourself. Nows a good time for cams if you have evar thought about em. I put in crowers for a little incentive to put it all back together. NEways good luck keep us posted.

Matt

CrazieLude · 09-13-2003, 04:44 AM

after further inspection. on the pistons. you can see what appears to be where the valves struck on the exhaust side. all of the carbon is gone. and you can see a "semi-circle" where there is no carbon and can see the piston. and a slight imprint of the "valves". i don't have a digital camera so i can't show you what i'm seeing but i'm allmost dead positive i floated the valves and struck the pistsons. but oh yes. i plan on slowly building this motor back up and taking the lude out of commission temporarilly.

but yes we took the lower intake manifold out with the head. lol. to much of a hastle with taking the manifold off.

thanks matt for your help. i'll keep things up to date and keep you guys posted on the news.

Preyluder · 09-13-2003, 11:10 AM

While you're at it, I'd open the block and take a look at the connecting rods, the piston rings, and all of the bearings (especially the main bearings).

4bidden · 09-13-2003, 11:46 AM

Yea, sounds like you killed all your exhaust valves.

When you said you could feel how some valves dont sit down in the head as far, thats because they're bent. That is also why the car wont idle.

Depending on how long you ran the car with this problem, the head can still be pretty easy to fix.

The white is normal. The cracks you see is probably just from the tiny flex when the valves hit the pistons. I doubt the valve itself is cracked.

Looks like youre in for 8 new exhaust valves and some machine work to seat them in.

CrazieLude · 09-13-2003, 06:54 PM

thats what i was thinkin. thanks jeremy.

btw. i only drive it like that for about 2-3 miles. just so i could get home.