McRibsz24

I had my '83 928s (US) rear end up on 8" ramps for about and hour to swap the fuel pump and filter. When I tried to start it and continue driving it it struggled to start almost like the engine was starting to lock up. Once it started it poured white smoke and started burning coolant really bad, coolant is also mixing with oil leaving it looking like chocolate milk. The oil level stays in a normal range and the engine is still running as it did (after the initial struggle from being on the ramps. I'm thinking head gaskets as that's the go to for coolant mixing/burning but I just don't understand how or if they could have failed so instantly and so horribly. Is there anything else (and maybe less intensive) that could cause this sort of coolant leak? I've looked all over for a similar abrupt and extreme coolant leak/mix/burn and haven't seen any other examples of this issue. The engine ran fine and didn't burn coolant or oil before the fuel pump/filter procedure. Thanks in advance for any advice or tips.

The Forgotten On

Probably just coincidence. Stop running the car and pull the plugs, crank the engine with the fuel pump fuse pulled and see which cylinders are filling with coolant.

There is no other way for coolant to mix with oil aside from the cooler in the rad, but that wouldn't fill the cylinders with coolant.

Your head gaskets have definitely failed and were on borrowed time, hell, all of us still running original gaskets are on borrowed time at this point, yours lasted 40 years!

545svk

Fuel injector stuck open?
Had similar symptoms when we did my son's Miata's cambelt and damaged an injector. Thick white smoke and no real smell. Also black fluid from the tail pipe.
Perhaps some crud made it from the tank to the injector.

McRibsz24

Thats was I was thinking, I just thought it was weird how they would go out in an instant like that. with all the cars I've seen with going head gaskets its sort of been a gradual fail with less smoke and not such a horrible smell. when mine went id rive for a few seconds down the road and the entire road was smoke screened. ill check the plugs and cylinders for leaks (compression and coolant leak test this weekend) and hopefully find the culprit. I've got some new head gaskets lying around so I might as well just swap them anyways. Thanks for the insight

FredR

The oil and coolant systems wil cross contaminate in the event of a failure in the radiator but as Blake says when it also shows in the exhuast system then a head gasket[s] for sure has gone sad to say.

When you pull the heads please take photos of the heads as they emerged and both sides of the gaskets. It is a fair bet you will have corrosion damage on one or both of the heads and short of changing the gaskets out many years ago nothing that could have been done to prevent such.

545svk

This is what the Miata looked like with the stuck injector.

McRibsz24

That's what mine looks like, I know the head gaskets are my main priority but I'm sure the fuel injectors need some work too. Did that smell weird or did it just smell like exhaust/uneven burning?

545svk

No real smell, but more oily than the sweet smell of coolant.

I have now twice mistaken issues for head gaskets - this time on the Miata and another on my s4 when the water pump failed.

I'd suggest getting a test kit to look for carbon monoxide in the cooling system before removing heads etc. Unless of course you want to do the head gaskets and all that goes with it in any case.