Oil in water

[Jonny5]

Im currently 300miles in to running in my rebuilt engine an im suffering from bad mayo in my expansion tank. Had a sniffer test done for exhaust gases in coolant an didnt change colour at all.Car is showing no signs of poor or rough running. She idles and drives really nice, heats up nicely, never overheats and sits half way on the gauge all the time when crusing. The oil has been changed twice and both times perfectly water free. No smoke from exhaust and heaters work fine. Drained coolant today and all the top hoses have oil in them an when flushing could see oil sitting on top of the water in bucket.
It hasnt use hardly any oil only some from a small leak from the turbo return hose.
Im at a loss as to what could be the cause as car runs perfectly apart from the oil in the water. I dont know where to look next as i cant keep buying parts that "might" fix it. Im running a nissa?? copper rad and im thinking crack between oil cooler and rad core? But cant understand why no water or mayo in oil.
Your help guys would be very much appreciated.

[Fordy]

sounds like rad failure tbh only easy way to check would be to get it pressure tested off the car

[Jonny5]

Ok so it seems like im looking in the right place then. Rad is off car ready for pressure test tomorrow.

[5teve L]

I had this on a car years ago, the oil cooler split & leaked into the rad itself.

[Jonny5]

If it has done that would there be no signs of water in oil at all? The rad was so called new from cgb and has only done 300 miles no mayo was present on initial start up after rebuild, but thinking back now there was a little oily film on surface. But as soon as engine came under load being driven the mayo started.

[Sparkie]

cracked oilway in the head.
its where the cast meets in the middle.
the oil pressure is greater than the water pressure, hence oil in water.

if you wanna check remove the plate at the end of the head and use a mirror. the oil way is right next to the plate - and so is the casting join....

[Jonny5]

I always thought a cracked head would cause poor running hmmmm something new to investigate.

[boostjunky]

I always thought a cracked head would cause poor running hmmmm something new to investigate.

If the break has penetrated the combustion chamber it can - oilway to water jacket would have no impact on running.

[Tony Walker]

cracked head or rad, the higher oil pressure in both cases causes oil to enter the water ways. Ive had the same thing, gradually filled my coolant system with mayo, if you take the end plate off the head you can just about see a crack where the oil comes through. you could run it for 20-30 seconds with no coolant in and plate off. you'll probably see the oil come out big crapness and i feel for you

[Jonny5]

Thanks guys get the lowdown on the rad tomorrow morning so fingers crossed its just that.

[Tony Walker]

stick an oil cooler on it to test, or some braided hose in a loop from one fitment to the other.

[Jonny5]

I need to get some more oil first dropped it to remove standard rad an see if it was a liner seal. Will it be ok running without coolant for a minute or so?

[Tony Walker]

you can run it for a little bit, i'd keep your hand on the head(not the rocker cover), when it starts to feel hot switch it off. dont let it get too hot to touch sorta thing.

[Jonny5]

Rads ok off it is with the head then.

[Jonny5]

Well me an my dad stripped the engine down an removed the head last night and its scrap.
Looks to have previously been welded turbo end on the cast line like sparkie said.
So new head sorted. My dads running round today trying to get some snapped studs out of it and pressure tested before building it back up.
Also is it normal for the odd valve stem seal to lift off its seat as i had two do it on the head i took off.

[Sparkie]

you can get the hole bored out and a tube epoxied in.

[Jonny5]

Not much point really the head is measuring about 72.9 so dont really know why we used it in the first place. New one is 73.5 ish an with a little work done by one of my dads engineering mates will be a better bet long term.

[Tony Walker]

probably a good thing really, if you'd stuck with that head and upped the boost much you may of ended up detting the engine, silver lining and all that........... (ps my stem seals came off too, stupid uprated things, stick with std imo. unless yours are just old and gone hard?

[Jonny5]

Im struggling to the believe the silver lining thing right now with the engine in lots of pieces after only 300miles, but yeah i know what you mean as was planning on 18psi after running in. They were uprated seals. Is this a common problem? Were could i get standard ones from?

[Tony Walker]

Renault will be cheap enough for them, you probably wont notice a difference if one or two come off.

[Jonny5]

Right i confused now. Tonight i took all the valves out the scrap head an im unsure if anything is actually wrong with it.See picture below, just above the second bolt hole at the bottom is what i believe to be a lump of tig weld. Its not on any of my spare heads. Ive had a good look down what i believe to be the one and only oil way for the rocker shaft an all
seems good. So i cant possibly see how oil could enter the water jacket in any way???

[Tony Walker]

Difficult to see with the pic but i think its here that they crack.

[Jonny5]

Thats what i though.

[Fordy]

oil will be coming out of the oil gallery crack into the water that runs around the head behind that cover you removed and then it'll return to the header tank

[Jonny5]

Well my dads found a crack big enough to push a stanley blade in as seen in pic below. Its in the area you said tony as well so looks like problem found.

[Jonny5]

Turned out not to be a crack after all. I had forgot to put steel washers under the headbolts which in turn caused the head to lift.
Ah well, they say you learn from your mistakes.