Headgasket? Or Piston Rings? :(

[Paulusc44]

Just took the RB25DE+T for a drive, has ran well, has all the sensible mods etc..

However Ive just returned home and found oil in my coolant

There was oil on the underside of the bonnet too, it had obviously come from the dipstick, which was about 20mm a jar.. Oil had a little water in as far as I could see

Im not OVERLY concerned if its just my headgasket, But would be gutted if it was my piston rings aswell..

How can I check this without cracking the engine? The car still runs well and blows little to no smoke, which is making me think its possible just the headgasket..

Cheers guys

[Deano 1]

leak down tester

[Griffin]

Any moisture coming from the breather?

[Ben C34]

What are sensible mods?

A tune?

[KiwiRS4T]

Sadly the RB will still go like the clappers on 5 cylinders so prepare for the worst.

A compression test would be the first step followed by a leakdown test if necessary.

[admS15]

Oil in coolant, definitely head gasket. You may have other issues too but that is a classic hg symptom.

[GTRPSI]

Lifting a dip stick is related to ring blowbye, not head gasket if the oil is not milky white, milky white oil then yes possibly a blown head gasket or split bore.

Dig deeper, check out under the oil filler cap for whitish gunk, oil in water, water in oil and pull the plugs out to check for the miss fire and pay attention to the color of the plugs.

If one of the plugs is rusted or really clean, id say water is getting into that cylinder.

[Paulusc44]

I understand the dip-stick being moved is due to blow-by but I had no breather hooked up when it was running.. could pressure have built up and forced a little pressure past the rings and into the crank case? Would I not be experiencing some heavy white smoke if my rings were destroyed? There is a small amount of white gunk under te oil filler cap, small amounts of water in oil and vice versa.. God Im hoping its just my head gasket..

[GTSBoy]

Oil control rings and compression rings are 2 different things.

[tasty_danish]

Pressure will certainly build up with no breather or with just a VTA type of setup. RB's seem to suffer from worn but not yet destroyed rings very widely. AKA: the engine runs/pulls great but builds up crank pressure/has oiling issues. That said, you have a bad headgasket. you may have slightly worn rings, but it may not be too brutal, however your headgasket is fuxxed. do a leak down and compression test. the gasket may mess with your results but I doubt every cylinder is busted and the ones that aren't may give you a good idea of the health of your rings.

What kind of mileage are we talking? depending on how much you cherish the car, new rings and a headgasket would not be a stupid investment regardless. I bet your rings are fine but old, and your gasket is totally out to lunch.

[Paulusc44]

Oil control rings and compression rings are 2 different things.

Lol Im pretty sure anyone with even the most basic knowledge of engines would know this.. Blow-by in the crank-case isnt going to be created from a failed oil control ring.. A failed compression ring or ring land on the piston however can and possibly will create blow-by, a failed oil control ring is likely to result in small to moderate amounts of oil being pulled into the compression chamber..

UPDATE:

Have just un-plumbed both breathers from the valve covers and taken the car for another drive, absolutley no blow by whatsoever this time.. I really do think this is just headgasket.. Will be doing a full Compression + Leak Down test in the coming days and will upload details..

The engines still blowing little to no smoke at all, but I would imagine that will change as the head gasket futher deteriorates..

[Paulusc44]

Pressure will certainly build up with no breather or with just a VTA type of setup. RB's seem to suffer from worn but not yet destroyed rings very widely. AKA: the engine runs/pulls great but builds up crank pressure/has oiling issues. That said, you have a bad headgasket. you may have slightly worn rings, but it may not be too brutal, however your headgasket is fuxxed. do a leak down and compression test. the gasket may mess with your results but I doubt every cylinder is busted and the ones that aren't may give you a good idea of the health of your rings.

What kind of mileage are we talking? depending on how much you cherish the car, new rings and a headgasket would not be a stupid investment regardless. I bet your rings are fine but old, and your gasket is totally out to lunch.

Thankyou Man, great reply! I have just opened up the breathers on the valve covers as they were both plumbed in, no blow by what so ever this time.. I only ever use synthetic Valvoline lubes (VR-1 or Full syn) and prestone coolants, all of the parts I use are genuine Nissan, well cherised car with 180,000 on the odo..

Im beginning to really think its just my headgasket, the blow by seems to have been created from a lack of breathing ability.. However as already stated a compression and then leak down test will confirm this.

If its just the headgasket Im not at all concerned as its just an op to add a Steel HG, GT-R 440'S, Z32 AFM and possibly an upgraded turbo to boot. Will see

[tasty_danish]

just know that with that much mileage it's likely that your rings are letting some gas by. most skylines do it. your car could do another 180K just fine, but temper your expectations. what you described is exactly why VTA catch cans suck. Your crank case needs some vacuum on it to perform as it should.

[Paulusc44]

just know that with that much mileage it's likely that your rings are letting some gas by. most skylines do it. your car could do another 180K just fine, but temper your expectations. what you described is exactly why VTA catch cans suck. Your crank case needs some vacuum on it to perform as it should.

Yeah as soon as the breathers on the valve cover were un-plumbed all blow-by stopped, Im now 90 percent sure that the dip-stick being blown out of place was due to the crank-case not being able to breathe.. There is NO reason as to why my rings would have gone.. But All will be confirmed with a simple compression and then leak-down test Fingers crossed!

[SkudR33]

I cracked the ring landing in between the two compression rings in my rb25det about a year ago - let me tell you, you'll definitely know. It turned my engine into a massive oil pump, literally had oil getting sprayed out of my breathers. It also started sounding like a wrx... Lol

[hardsteppa]

Wait, this DE-T engine is the same one that you set the timing on by eye, rather than using a timing light?

[SkudR33]

Wait, this DE-T engine is the same one that you set the timing on by eye, rather than using a timing light?

You align the gears against the marks by eye but then you need a timing light to set the CAS in the right position [emoji4]

[Paulusc44]

No, I set this engine to the standard 15* using the cam and crank marks, then a light.. but I then backed the CAS off 2mm Clockwise which would equate to 12* timing..

[Ben C34]

What

[tridentt150v]

Why would you do that?? 15* is 15* and at 650 rpm so the engine needs to be warm and idle settled. Plus a little movement on the CAS is a lot of timing, or thats what I've found.