Datsun Roadster Forum-311s.org

ok checked the #3 with oil , only gained 5 psi..so its not bad rings...
changed plus agian to colder still the same thing..i am so lost and frustrated, im about to buy a ka24e and put it in here!!!

steve

If you do the leakdown test, you will have your answer. Might just be a head gasket or leaky valve, neither one is too bad. This brings about the big question, If you want major horsepower in the future, maybe it is time to gather parts and money for a swap instead of getting too deep in a motor you won't keep.

well im pulling the head off today...i just put this head gasket on it! theres no mixing of fluids so everyone seems to think its a valve..no biggie i hope.

im going to go look at a 240 with a motor w/the head off..don't know about it, but its only $500 so it might be worth while.

ill let you know as soon as i have the head off guys.

thanks
steve

both valve weren't sealed to the seat..a good 1/2 in. so this seems to be the problem. I have to fins some valve lapping compund. No luck yet. I think my mom is going to buy this car, as im buying a new car (crossfire or srt10 ram) and im going to be getting another roadster as a project. H20 turbo efi engine...The car i have now is nice and complete...plus i want to put a diff rearend in it. etc etc

thanks
steve

Steve,

Don't give up yet! I have some valve lapping compound out in the garage somewhere. If you can't find some, let me know and I will dig mine out - come by and we can lap those valves...

Get this one running and enjoy it - then look for the "project" car for the H20 monster motor and such.

Another well hidden "simple" problem. Glad you took the time to diagnose it, pain in the butt, but good experience.
Any decent speed shop should have compound, or Napa can order. Just make sure you clean up all the excess and flush it out with brake cleaner.
You might want to do the valve seals while the head is off, much easier.

How did you determine the #3 cylinder valves were not sealing to the seat after you pulled the head? And if they weren't sealing, how come this was not revealed by the compression or leakdown tests?

Maybe a dumb question, but could the timing chain be off a notch?

Ray B

Correct me if I am wrong, but if you had the head worked over by a shop, shouldn't they have spotted the valve issue? I wonder if they are bent at this point. Either way, a couple of valves are cheap enough...

Now that I think about it, it should have shown up on the compression test.As long as your sure, all it will cost is a head gasket and a few hours to find out.

I looked at the seat of the valve and it was shiny only a little bit. the rest was black...showing that exhuast was going over it. it is very minute but enough to make the mixture lean. the cylinder was lower buy 25 psi to the rest of the them showing that it was this. as i added oil and it only gianed 4psi..showing not the rings.

I found some lapping compound and it is going back together today..hopefully have it runnging and drving.

thanks
steve

well it fixed the #3 cylinder..but theres more problems..still misfires (as in the compression is to high) so im pulling it out to cut some of the piston down..but i just might be putting h20 stuff while i have it out..along with the pistons....

thanks
steve