adamk

The situation: my 1994 Pickup with a 22RE has some slowly accumulating coolant mayo sludge under the oil fill cap.

This is a relatively new development and the most recent change to the engine was I went from crude to synthetic on my last oil change (at about 110,000 miles). No sludge under the cap at all prior to change.

Other info to help narrow possibilities:
- Coolant is slowly disappearing.
- No visible exterior coolant or oil leaks. Oil level holds steady.
- Did my timing chain, new steel guides, timing cover, tensioner, water pump, oil pump at 106,000. All went well, no leaks.
- Checked my compression after the white gunk showed up thinking it could be the head gasket, got 190psi in all four cylinders.
- Prior to the synthetic oil switch I ran a very modest amount of Seafoam in the oil for a little while, not too long.
- Spark plugs are oddly dirty, #3 the most, then #4. Plugs were changed at 106,000.
- Gas mileage totally sucks. Used to get mid to high 20's (2wd manual trans), lately can't break 18mpg, got as low as 13mpg on the last tank.
- The back of the head is slightly wet/oily, around where the EGR crossover plate is. Again, no oil leaks and level holds steady, so I don't think it's the valve cover gasket (replaced at 106,000 with timing chain).

I'm thinking the severe dip in mileage has to be related to the coolant in the oil. Could this be rooted in the wet EGR crossover plate? It's just about the only thing that's out of sorts.

Any thoughts?

L5wolvesf

Is there any coolant or "milk shake" in the oil?
When you did the chain did you look at the timing cover?

adamk

I got the full kit from engnbldr and it included a new timing chain cover. The old chain was bad and had snapped the plastic chain guides, but it was nowhere near cutting through the cover in to the water passage. This is the first time I have ever seen any sign of water in the oil. It accumulates very slowly on the bottom of the oil fill cap, as well a few teeny drops around the dip stick neck.

Co_94_PU

iTrader: (-1)

the wet spot on the backside could also be from one of the hoses, atleast those are easy to see uhm mostly

You have the PCV installed and the other vent at the front to the intake? Is the gasket/o-ring on the dipstick and oil cap in good shape?

adamk

Yep, PCV and breather hoses are on. Oil cap seal is good, dipstick seal leaves something to be desired (gettin a little hard, might not be properly sealing).

I have to imagine that the vacuum, breather, etc hoses are all original on this. I may just do them for good measure.

thook

http://www.pirate4x4.com/forum/toyot...ttle-body.html

DallasTX

Might want use a block test kit to check for exhaust fumes in the radiator to determine if the head gasket is blown. Get a loaner at AutoZone or O'Reily and it only cost you about $8.00 for the test fluid. See https://www.yotatech.com/forums/f116...xhaust-298425/ for more on this. Only other two places I know where water can get into the oil is the oil cooler, if you have one, and the passage in the throttle body.

L5wolvesf

Just a thought - condensation?

thefishguy77

iTrader: (1)

Yea if it sat for a few days then it could be condensation. 🤞

adamk

Whoa! This seems like it's exactly what I have going on, although to a higher degree. I'm not getting the volume that this guy was, but it's showing up in the same ways.
Compression test was perfect, but I suppose there's more than one way for a head gasket to go. Could be worth doing.
I thought this, too. It's barely sitting unused these days, though the trips are very short and in cold weather. Could explain the muck under the cap, but doesn't account for the missing coolant.


I ordered a new gasket for the auxiliary air valve, as well as all new vacuum, breather, PCV hoses, PCV valve and grommet. Hopefully something in there will do it. Will report back...

thook

What style of AAV do you have? Is it integrated with the TB or remote?

adamk

integrated with throttle body, four bolts attaching it to the bottom.

thook

It's possible the thermal wax valve is leaking. Not real likely given you don't have that many miles on the engine....relatively speaking. I mean, they do last a very long time.

92 Toyo

Coolant dissapearing could be your heater core? It would smell kind of a coolant sweet smell in the cab, or it can leak out of the connecting hoses at the firewall. If you have coolant in the engine you should have a lot of white smoke coming from the pipe. and you would know if your oil doesn't look like oil anymore. Bad gas mileage is probably your engine running too rich. MAF sensor all good? any other clues you have for us?

adamk

Is the Thermal Wax Valve in the AAV? If I remove the AAV how can I tell if the wax valve is good or not?

I got some parts in the mail the other day, new o-ring for the AAV, new vacuum/breather/PCV hoses, new PCV valve/seal. I just did the breather hose and PCV stuff on lunch break. The inside of the breather hose was clean (no white gunk) but the PCV hose & seal had a decent amount of the gunk coating the inside. Not enough to plug it, though.

Going to pull the TB and AAV next...

adamk

So I changed the o-ring-ish gasket between the TB and IACV. The original gasket was very compressed, hard and looked like it had signs of leakage. Because the IACV seems to function fine (idles up when cold, gets lower when warmed up, remains steady and doesn't surge.) I didn't replace the whole valve, just the gasket. Also of note: the inside of my intake (from the TB valve back) is majorly black, cruddy, nasty with about a 1/16" of semi-hard black paste junk all over everything. I cleaned the TB thoroughly, but didn't get down into the intake manifold for fear of dislodging some big chunk.

Took it for a nice long highway run at the usual 60mph as well as a good bit of driving around town and I've got the same white condensation sludge under the fill cap, maybe even more than before. Water that is collected on the cap seems to be clear. Throttle response seemed better and it's definitely idling smoother.

Can the Thermal Wax Valve in the IACV function fine with a small leak? That could explain the persistent moisture in my oil. I have a hard time believing it's just atmospheric moisture, as I've literally never had this amount of gunk build up on any other car I've owned, modern or classic (though never an old Toyota). Sould I just stop paying attention to the moisture in my oil and start looking elsewhere for solutions to the terrible mpg? EGR? O2 sensor? (The sleezeball hack I bought this from said he put a new O2 in just before I bought it) Bad cat causing power loss/harder driving? That crap inside the intake probably isn't helping...

I'm at a loss. I just want to like this truck

Co_94_PU

iTrader: (-1)

Forgive me if this was already covered I went back to the top to get a fresh take.

Was this remedied? That is the EGR coolant plate and should not be leaking, the only acceptable moister would be a leaking half moon seal on the valve cover (acceptable being a personal choice of course)..

This plate if
​​​​loose or damaged will allow the EGR system to suck in coolant and feed it to the intake. It's a trivial but cramped fix to put a new gasket on..

Again forgive me if it's the same truck that shorted out the battery attempting to remove the EGR Valve. I didn't read all the way through since that jumps off the page at me.

L5wolvesf

Is it just in the cap and not under the rocker cover? Another thought the oil cap gasket?

Co_94_PU

iTrader: (-1)

He has been doing the highway runs which would be boiling off any sort of crankcase condensation, bonus it boils off any fuel deposited there also and keeps the oil healthy.

adamk

No, I didn't do anything to my EGR yet. I think the external leak back there is probably the half moon (new), as the oily dirt starts high up on the head. Honestly, I'm fine with it.

The black goo inside the intake plenum was thickest around the TB, with what looked like a clean runny streak coming straight from the PCV, and over by the EGR inlet it was the cleanest (though still dirty). This could explain why my #3&4 plugs are always much dirtier than 1&2. Is the EGR coolant plate gasket a common failure?

I found this by way of Pirate 4x4, might go down this road after I confirm/repair the EGR plate gasket: http://www.wildyoats.com/hp_under_$95.htm

It's under the rocker cover, too, as well as inside the PCV hose and the top half of the dip stick. Oil cap gasket is original, but seems fine, no chunks missing and gets nice and tight.