93 Trans Sport 3.8L Oil in Coolant

The van and motor have approximately 400,000 km on them. I went out yesterday and removed the rad cap, and low and behold there is a layer of chocolate milk on the top of the AF. I am quite certain we have oil in the rad, so that could mean intake or head gaskets leaking.
I have no idea how long that problem has been developing. I had a leaky heater core for quite some time; I used some stop leak then. When I replaced the heater core I don't remember the oil in the AF.
I wonder if it's worth trying stop leak now to seal up the oil transfer? Would I use engine oil sealer, or coolant system sealer?
Has anybody changed head or intake gaskets on a 3.8L? How tough of a job is it being tucked away in the engine bay like that?

Can you pull the lifters without removing the heads on a GM 3.8L?
There is a tool, a small slide hammer that will reach through the push rod holes and pull the lifters out of the block. I wonder if it will work on a GM 3.8L engine?

If I recall, the lifters are retained in place to the black by a plastic retaining bracket, accessible only once the intake manifold is removed.
Are you sure it is engine oil in the coolant? Or could it possibly be automatic transmission fluid, indicating the heat exchanger in radiator has failed.
Changing the intake manifold is a bit of a pain, but can be removed in a couple hours while in the van. Just make sure you thoroughly clean everything before re assembly, including wiping it down with acetone , and use only The Right Stuff brand rtv, other cheaper brands will not stand up.
Again, removing the heads in place can be done, but it will be a pain getting everything out of the way, especially the rear exhaust manifiold.
How is the engine oil looking, any signs of coolant mixed with it?
Good luck

Jeff

If I recall, the lifters are retained in place to the black by a plastic retaining bracket, accessible only once the intake manifold is removed.
Are you sure it is engine oil in the coolant? Or could it possibly be automatic transmission fluid, indicating the heat exchanger in radiator has failed.
Changing the intake manifold is a bit of a pain, but can be removed in a couple hours while in the van. Just make sure you thoroughly clean everything before re assembly, including wiping it down with acetone , and use only The Right Stuff brand rtv, other cheaper brands will not stand up.
Again, removing the heads in place can be done, but it will be a pain getting everything out of the way, especially the rear exhaust manifiold.
How is the engine oil looking, any signs of coolant mixed with it?
Good luck

Jeff
1995TS,
Sorry for the slow response. I didn't get an email notification in my inbox. I suppose it landed in Junk.

I hope it's not head gaskets. I just finished doing them along with a head revamp on my 96 Chev K2500. I have had enough of that stuff for now; maybe feeling too old at present. There is only so much time.
I might run some head gasket tests, like looking for bubbles in the rad, and that gases test using the fluid that changes color.

I HOPE IT IS THE TRANSMISSION COOLER PART OF THE RAD! ��
I'd love to change a rad; amazon.ca has them for $170 CAD. There are probably even cheaper ones available like at Parts Shack etc..

I can see myself doing the lower intake. I used The Right Stuff gray on the intake 'end valleys' of the 5.7 Vortec in the 96 Chev. I wiped it down with brake cleaner but will try acetone on the 3.8 when I get there. I fretted that I had not put a wide enough bead down. My motto now is 'Lay a generous 1/4" bead' ... so far so good.
I used the FelPro intake gaskets that have been reverse engineered to forgivingly accommodate the repair scenario where the surfaces might not be the best.

I'd inspect the lifters taking them apart; If they aren't worn too much, soaking them in carb cleaner, and swabbing and blowing them clean out. I have more time than money now, and there is 400,000 km/250,000 mi on it.
I will check the engine oil dipstick real good, under the oil filler cap, and the tranny dipstick too for globuls and build up of milkshake.

I will keep a closer eye on my Junk folder (I just emptied it last night) because I always received notifications in the past.
Thanks a ton Jeff, for getting back.
tinkering

Does your van have the factory installed oil cooler? That routes oil from under the oil filter adapter to a cooler in the rad.
I am just trying to think where oil can get into a pressurized cooling system-the oil has to be under higher pressure for that to happen. So far the only place I can think of keeps leading back to the rad, but hopefully others will make suggestions.
Using brake clean on the parts rather than acetone should be fine. The main thing there is to make sure everything is meticulously clean and free of any oily residue before reassembly and using the RTV
Jeff