how does oil get into the coolant through a faulty inlet manifold gasket?

[admir87]

hello all,

ok, ive heard oil getting into the coolant and visversa through buggered inlet manifold gaskets, but where does the coolant and oil pass through the manifold? looking at pictures of a gasket i can see the coolant passages, but cant see where the oil passes through,

so how does oil get into the coolant?

cheers

[Brett_jjj]

Coolant leaks into the cylinders from the coolant passages in the inlet manifold where it joins the heads if the inlet manifold gasket blows or leaks. Coolant leaks down into the inlet ports of the head(s) and in past the valves(it wont get past the valves when they are shut but the engine rarely stops with the valve in the fully closed position,and coolant would pool up in the inlet port and it would be sucked into the cylinder when the engine is started anyway), then seeps past the rings and into crankcase and into the oil.It can also get pushed past the rings under compression if the cylinder has a fair bit of coolant in it when the engine gets wound over (started).(it can actually stop the engine winding over at all in some cases).I had an engine that was sucking in water from the coolant passage then into the inlet ports of the engine and then spat out the exhaust pipe.You know the gaskets are leaking badly once this starts to happen.(lots of steam too).Theres no oil passages going into the inlet manifold from the heads.

[admir87]

hi brett, ye i understood how the coolant would get into the combustion and rest of engine, but what i dont understand is how people get oil into the coolant through blown manifold gaskets.

like when you notice it in the radiator

[RX25SE]

Oil can also leak directly into the valley of the motor once the engine is shut down. The cooling system is still under about 120kpa pressure and the crankcase is at atmospheric pressure.
As the engine cools, the cooling system pressure falls. The pressure eventually goes slightly below atmospheric (when the vacuum valve in the radiator cap opens) so it will draw in some oil through the faulty manifold gasket.

When I did mine there was oily residue under the radiator cap and inside the coolant overflow bottle. I couldn't really tell if any went through the combustion chamber.

BTW. I have seen them when coolant leaks out of the manifold bolts. Travels up the threads and leaks out under the head of the bolt.

[The1]

i just did my gaskets and seals, mine from what i can tell was sucking in oil to the coolant, spark plugs were burining fine and engine running fine, oil was clean. Seems to be ok after changing the gaskets

[Brett_jjj]

Oil mostly gets mixed with coolant when a head gasket blows,or through a cracked head/block.Ive never seen a blown inlet manifold gasket leak oil into the cooling system,(and ive fixed a fair few of these).Its located at the top of the engine plus theres no oil passages that pass through the inlet manifold gasket to leak.And theres no pressure in the crankcase,its kept at a vacuum from the PCV valve while its running.As soon as the engine is turned off the oil drains from the crankcase and rocker covers straight down to the sump.

[The1]

well my pcv valve was stuffed and i found the oil seperator wasn't installed properly, obviously pcv was changed before i owned the car and wasn't put in properly.

[Brett_jjj]

If the oil seperator in the PCV is not working all that will happen is oil will be drawn into the cylinders and burned in the combustion process.Its not gonna end up in the cooling system.

[The1]

well the 2 old gaskets that came off the bottom part the rubber had perished on the rear 2 inlets for the coolant where it's blocked off by the intake manifold, this is where the oil was builtup, i couldn't find oil anywhere else, spark plugs are burning perfect, engine running perfect, compression perfect, oil is clean as, so i dont know, im just a self tought person keeping my car going and trying to save money, it seemed pretty obvious where the oil was coming from when looking at the manifold, i will post up a photo tonight of it if the OP doesn't mind

[admir87]

ye mate no problems, would like to see it

[Brett_jjj]

If the gasket is broken where the coolant passage passes into the inlet manifiold from the head there would be coolant (which is under heaps of pressure when its hot)leaking into the crankcase.It wouldnt get oil into the coolant passage unless there was a vacuum in the cooling system,Which only happens when the engine has fully cooled down.Weird.Also once oil is in the crankcase it is not under pressure,it uses gravity to run back to the sump, so it cant really get "pumped or pushed under pressure"into the coolant passage either.

[The1]

yeh i know what you mean, when i had it all apart i looked over the whole top end, clean as, no coolant in there anywhere, it never used any coolant at all, i drained the old oil out before starting it the first time and it was clean to. Ill be dropping the new oil out again on the weekend to check again but the dipstick still looks very clean.

[Brett_jjj]

Its certainly a strange thing thats going on there.

[admir87]

ive heard many people with oil in the rediator, and it ends up been a stuffed manifold gasket

i was just looking at pics of a head, there are open passages that pass oil through the head(eg where the pushrods pass through is open to the inlet gasket) yet its blocked to the manifold by the gasket, so i guess if there is a crack in the gasket it would leak that oil into coolant and inlet passages

[The1]

here's the photos, it was just the rear ones that had the issue, you can see it weaping in from the bolt hole and various other places, mine was still the original, funny that in the geniune holden service manual it says to use gasket goo around the bolt holes and locktight on the bolts... Yet my factory gaskets and bolts had nothing

[The1]

also i noticed that the bolts that came out had part of the bolt worn down a bit compaired to the rest of the bolt which was very clean with perfect thread, i guess it's possible that part of some bolts go through a internal passageway for oil which would then cause this leak over time through the bolt hole?

[Brett_jjj]

Usually you would see stuff like that with a blown head gasket when the gasket blows out near an oil gallery where it passes through to the head.I just has a quick read of a gregorys workshop manual for a VS ecotec and it doesnt mention sealant on any of the bolts except the main head bolts.It says to use locktite or similar on the inlet manifold bolts though.Thats how my inlet manifold gasket blew out.All the inlet manifold bolts were finger tight.It was a fairly new reconditioned engine from redlands in brisbane.Had about 10,000 ks on it when I got it,it was crook and this is what I found,blown inlet manifold gasket and loose manifold bolts.

[moff_man]

here's the photos, it was just the rear ones that had the issue, you can see it weaping in from the bolt hole and various other places, mine was still the original, funny that in the geniune holden service manual it says to use gasket goo around the bolt holes and locktight on the bolts... Yet my factory gaskets and bolts had nothing

If you look at your mainfold you will notice the 2 rear ports are blocked this is why you have the build up, i am currently doing the exact same job at work, if look at the front water ports you can see a circuler hole just above the port on both sides this is where the oil gets sucked in to the water jackets as it runs down.

the gaskets brake up over time and this is when the gaskets start leaking. (the job im doing at work is on a WH statesman with 290xxx km on the clock)

edit: vr inlet manifold's have 3 ports open on the manifold where as vs onwads (ecotec) has 2, its just a coolent transfer bye the looks of it between heads

[Brett_jjj]

That hole is where its getting in once the gasket blows out,that is one of the inlet manifold bolt holes above the coolant passage.The gasket doesnt look blown out there though in that pic..When I did mine there was a big cracked off piece of gasket missing,and you could see where the coolant had been going from the coolant passage to the inlet port .

[moff_man]

yes, i will add thet they all blow in diffrent spots as well

[admir87]

If you look at your mainfold you will notice the 2 rear ports are blocked this is why you have the build up, i am currently doing the exact same job at work, if look at the front water ports you can see a circuler hole just above the port on both sides this is where the oil gets sucked in to the water jackets as it runs down.

the gaskets brake up over time and this is when the gaskets start leaking. (the job im doing at work is on a WH statesman with 290xxx km on the clock)

edit: vr inlet manifold's have 3 ports open on the manifold where as vs onwads (ecotec) has 2, its just a coolent transfer bye the looks of it between heads

moffman,
what do you mean by the 2 rear ports are blocked off?

cheers

[v6lux]

Here is what happened to mine

[moff_man]

moffman,
what do you mean by the 2 rear ports are blocked off?

cheers

have a look at the manifold it self and you will see 2 ports cast over, i try and get a pic of the wh one im doing at work. copaired to the the vr one i have in my shed