rb25 wont start and knocking

[branmr2]

I think I screwed something up in my rb25det! I turned on my road the other day and went wot, when i did i noticed some stuttering or detonation or something. then when i pressed the gas again it acted as if it was running on 5 cylinders and had some knock. it ran long enough to get me home and started back a couple times but knocked. After some messing around with it I cant even get it to start again. I took the intake manifold off and the inside of the head and the #6 runner are black as coal. all the others are fine looking. Any opnions on what the trouble might be before i tear it down farther. anyone have a cheap rb25 for sale?

[240z4u]

You need to do a compression test. Is the exhaust port oily?

Knocking? Check your oil for bits of excitement.

[branmr2]

Compression was same in all six, over 100 but dont remember the exact number. I havent taken the exhaust manifold off yet or drained the oil. I have only drained the coolant and taken off the intake. It is a pretty warm day today i may drain the oil in a bit.

[240z4u]

carefully cut open your oil filter and check it out. Don't open it with a saw, which will obviously add its own metal filings.

Good luck.

Its 7 degrees here LOL.

[Carl H]

sounds like the timing belt might have slipped...

[branmr2]

I will check the timing and make sure everything lines up properly.So carl h, you are in charlotte nc? Do you have a shop, It would be great to have someone close by to consult with. Do you work on rb's for people or just your own stuff? I am only about an hour from you depending on which side of charlotte you are on.
Modified by branmr2 at 9:54 AM 12/8/2007

[QuickerThanU]

Lol, sounds more like u spun a rod bearing. If it still drove when you did that **** and was seriously knockin and hesitatin i doubt it would be slipped timin belt but its possible. I did that **** in mine and had exact same symptons (knockin, hesitating, lost damn near all useable power but i was able to drive mine a mile home but it would start sometimes at first but engine would clunk and knocked so bad) turned out to be spun bearing.

[branmr2]

did you fix it or swap in another motor? If you dont mind me askin, bout how much did u spend fixin it? I checked the timing today, the belt was a little loose, it may have been a tooth or so off. it would be easier to just swap another motor in i guess. I just hate to do that cause the one in it now has been bored 20 0ver , forged pistons, shot peened and cryo treated rods, cometic head gasket, arp studs, balanced. the motor was already in the car when i got it, thats just some of the stuff that I was told was done. either way my wallet is gonna get thinner!

[branmr2]

b

[QuickerThanU]

All that work done and you still spun a rod bearing? Maybe the guy was bs'in you. But it might not be spun rod bearing. I just know my car had exact same symptons as you and i suspected the bearing and my mechanic comfirmed it. I just put a new motor in it though. Take it to a shop and get it verified by an expert before you do anything drastic.

[Coolwhip]

might of craked ring land, my SR did the same thing. but oil was shooting out the exhuast

[branmr2]

pulled the engine yesterday and while i was working on pulling the head off i found what i think was the problem or at least the cause of my problems. when i pulled the exhaust side cam cover i noticed that the #7 exhaust cam journal was loose. I pulled on it and it just came right out, both of the threads were stripped out. On top of that i also noticed that the cam was broke off right past the first exhaust valve on #5. Now i either need a head or at least some rb25det s1 cams. If i reuse the head i will have to get several journals drilled and retapped cause the bolts broke off when i removed the journal. I guess i will have to wait and see if I can find a head at a good price.

[grenade180sx]

pulled the engine yesterday and while i was working on pulling the head off i found what i think was the problem or at least the cause of my problems. when i pulled the exhaust side cam cover i noticed that the #7 exhaust cam journal was loose. I pulled on it and it just came right out, both of the threads were stripped out. On top of that i also noticed that the cam was broke off right past the first exhaust valve on #5. Now i either need a head or at least some rb25det s1 cams. If i reuse the head i will have to get several journals drilled and retapped cause the bolts broke off when i removed the journal. I guess i will have to wait and see if I can find a head at a good price.

Good head is hard to find.

with that aside you still hae a bottom end to worry about. if you going to go as far as doing head work might as well rebuild your whole motor.

or get another engine

[branmr2]

was already built, just gonna check out the cylinder walls if they still look good ill prob leave it alone

[Cjmartz2k]

What he's getting at is anything involving you cams involves valves and this is an interference motor. You might have a bent one or a hole in your piston or something.

[branmr2]

yea i know what he is talkin bout, I am gonna check it all before reassembly hopefully nothing else is trashed.