Inlet Valve Leaking! Where Do I Go From Here?

[Seano93]

Hi guys,

New guy here looking for some advice on where to go next in my diagnosis.

I have a '96 R33 GTS-T pretty much stock, it started running a bit rough a couple of months back but i only just got off my ass to investigate it.

So i checked my spark plugs, found cylinder 6 was black/ oily. I did a compression test, the first 5 cylinders showed 120psi, but the 6th cylinder showed only 20psi....... yes, 20. We didn't have a proper cylinder leakage tester but i had a connecter and plugged an air line into the spark plug bore with the engine at TDC and air came rushing out of the pod filter.

So obviously there is a problem with the inlet valve/s on cylinder 6?

I was hoping you guys could give me some insight into what the actual problem might be and how i go about confirming and rectifying the issue? And will i have to replace rings as well? Im not sure where to go from here and how much work im looking at. I was planning on selling the car soon so i dont want to spend too much time and money on it.

Your input would be appreciated,

Cheers, Sean.

[Ben C34]

You have to at least take the head off to fix it.

Remove head and report back.

[Dose Pipe Sutututu]

Probably be more coat effective to replace motor with a used lump with good compression since you're selling it anyway

Say of you pull the head then find out your piston ring lands are smashed, there's more money gone.

Sad reality isn't it? But these cars are old and they break

[Humbla]

Probably be more coat effective to replace motor with a used lump with good compression since you're selling it anyway

Say of you pull the head then find out your piston ring lands are smashed, there's more money gone.

Sad reality isn't it? But these cars are old and they break

Mine only broke due to some one else's boo boo,if you take care of your engine they last,nearly 300000 on second hand motor on my old 33

do 30000 plus a year on mine so they do last. :-)

[Dose Pipe Sutututu]

Mines probably got 300000 km on it too - judging from the body and car bushing etc. Clock says 140000 lol

Has had a good hair cut from dealers and previous 50+ owners.

I'm too scared to do a compression test on mine in fear of getting sad. It cops a beating on the track and regularly sees 1.5bar through the motor. It's going to pop soon I reckon lol

[scotty nm35]

Mine is in a similar condition Johnny, 200,000+ks, goes through 2L of oil in 5k, the bores were very scuffed when I had the head off. It just refuses to die, even my tuner is amazed. It still cops 32psi daily, i'm not tracking it anymore but it survived 8 track days, overheating to 150c quite a few times, and over 200 power runs on the dyno... Some of which caused a head to lift.

The only reason I think it is still going at all is because I have a spare engine waiting to go in. If I sold it the engine would blow the next day. Regular maintenance, good fuel and tuning are my reasoning though.

To the OP, rip the head off, if there is anything wrong it's time for a wrecker motor I think. Make sure you can compression test the s/h motor in the car if possible, and check the oil filler cap and inside the rockers for carbon buildup which would indicate poor servicing with crap oil.

[Dose Pipe Sutututu]

your motor is just scared of being replaced so it's behaving LOL

it's sad we will never truly know the real KMs on these import unless it's come straight from Japan with authentic japanese deregistration & auction papers

[jiffo]

Just because the engine was at TDC doesn't mean it was firing on No 6.

Could just as easily been firing on No 1 which could explain air rushing from No6's inlet valves.

To eliminate the guesswork, one would rotate the crank another rev and perform the test again.

Then you'd have a better idea if it was a valve or a piston problem.

No matter in the long run, 20psi compression test is a mega fail.