8v 530 cooling system pressure loss...

[blkaplan]

So I have an issue with my attempted DD 92 245.

The car at one point sprung a HG, lost the sealing ring between 1-2.

When we had the head off we noticed a good bit of corrosion on the blind holes that the HG lets coolant through, especially by the back of the head.

Im guessing PO ran straight water for while leading to the corrosion.

I removed the porous material and filled the gap with our best friend JB... and decked it flat.

There are signs of a slow leak of water potentially getting into the oil. On the top of the oil fill cap it looks mildly cloudy, and the pcv has a little bit of white in it. The oil for the most part looks completely normal and there's no "milkshake"

The expansion tank dropped from the middle to the bottom on a 40 mile drive.

I put a pressure tester on the expansion tank and pumped it to 10 psi. over about 20 minutes it dropped down to 8psi. We visually inspected as much as we could and did not see any place where the water could be leaking externally.

I left it pressurized when I left to see if it would hold over the weekend.

Any thoughts? My guess is there is a crack somewhere internally in the head letting the coolant wheep into the non pressurized oil drain back....

 

[Kjets On a Plane]

Exhaust sniffer on the coolant bottle / coolant strips? Spark plugs? Misses cold?

I've seen crack in the exhaust port on a bad over-heat way more or corroded on the block deck by now.
Won't necessarily pressurize the cooling system or overheat.
I haven't seen cracked into the oil on the Volvo SOHC Head. I'm sure it's possible...just I'd expect to see cracked into the exhaust port first.

The oil feed is in the middle and small and the drains are a long ways from the exhaust ports & the head is crazy tall/an oil lake. Other stuff fails first.

Lots I haven't seen...dye in the coolant and look in the exhaust port or sniff it?

Head original height or have some cam rattle like it overheated? Late heads are a lot more ductile/less prone to crack after 1990, but they also are more prone to cam rattle.

It's the chlorine and minerals in tap water that causes the corrosion...I use collected condensate off the the heat-pump water heater; already has aluminum/zync contact from the condenser, but no chlorine or minerals, really. Don't necessarily have to buy DI water though...it would be nice if all engines were that clean, but once they're used the dust isn't going to decide it.

It's all a long winded way of saying, humid swamp DC/MD climate and cooler weather & car sits (outside a bit?); I think the PCV & oil cap milk (or sneeze?) is a red herring, but what do I know?
All I know is if they don't get highway driven and sit hardly at all in that climate over the warm swampy ground in the fall with the cooler air on a tractor engine with hot/cold spots with the late style no thru-breathing crankcase vent, it's real easy to see that milk/sneeze from the crankcase vent & under the oil cap that looks a little gross & doesn't really go away?
If it was in a super dry roofed structure in AZ or even drier and there was milk while driving it *at all*, I'd weight that heavier.

Or maybe you'll catch a break & it's just the heater core got borked by the corrosion or valve or water pump hat seal or weep hole or T-stat housing is super pitted and it's hard to see/running down the ledge along side the driver side of the head that overhangs? Dye and really look over that stuff just in case, the blind holes at the back just aren't *that* close to oil.

 

[culberro]

Oil cap snot is pretty common if the engine sat for a while, especially if in a humid area. It’ll usually clear up pretty quickly once the oil gets got and burns off the moisture.

Heads do leak from time to time into the oil drains. Pressure testing the head during a rebuild is a must to find these issues. You can also do a UV dye in the coolant and see if that comes up (like what Brian did on the CNC RSI head that was leaking, which was from an internal casting defect most likely).

 

[blkaplan]

Oil cap snot is pretty common if the engine sat for a while, especially if in a humid area. It’ll usually clear up pretty quickly once the oil gets got and burns off the moisture.

Heads do leak from time to time into the oil drains. Pressure testing the head during a rebuild is a must to find these issues. You can also do a UV dye in the coolant and see if that comes up (like what Brian did on the CNC RSI head that was leaking, which was from an internal casting defect most likely).

Whats the easiest/best way to pressure test the head?

Car sat over the weekend with a pressure tester on the system, psi went from 7psi to around 5... not bad? Glad I didn't come into a gage reading 0. I proceeded to drive the car around 70 miles yesterday. Milky coolant from oil cap seems to be gone. Coolant level might have dropped a hair? Definitely did not empty the overflow.

Have been leaving the overflow pressure cap just barely snug.

 

[culberro]

Whats the easiest/best way to pressure test the head?

Car sat over the weekend with a pressure tester on the system, psi went from 7psi to around 5... not bad? Glad I didn't come into a gage reading 0. I proceeded to drive the car around 70 miles yesterday. Milky coolant from oil cap seems to be gone.

I use a setup that closes off all of the coolant passages and allows me to pressurize them with air. I then use a soap/water mixture to look for cracks. Works very well.

On car, you might be able to add a UV dye to the coolant and then pressurize it. Then pull the valve cover and see if you can see any dye showing up.

It sounds like the milky cap was just residual condensation. The pressure drop seems reasonable given the number of possible leaks in the system.

 

[blkaplan]

We did see the water pump needed to be reseated. maybe that's where my initial volume loss came from.

Ill keep driving and monitoring it.

 

[gsellstr]

Any oil cooler setup on it that's connected to the cooling system? 940 oil/water setup or something like that? I've seen the in-tank coolers in the radiator leak on P80's, causing that slight mixing. Just throwing it out there.

Definitely curious what turns up...

 

[blkaplan]

Any oil cooler setup on it that's connected to the cooling system? 940 oil/water setup or something like that? I've seen the in-tank coolers in the radiator leak on P80's, causing that slight mixing. Just throwing it out there.

Definitely curious what turns up...

Its a NA 92 m47 car, so no oil cooler, and no transcooler hooked up either. Its possible that some water could be going into the transcooler area in the radiator I suppose. Its a new radiator but that might not mean much now a days.

I had the transcooler fail on my 960 and let antifreeze go into the auto and roast it.


Car just passed emission so now I can beat on it and see if things stay stable.

I was letting er rip on the way to work after the inspection and coolant level seems to be fairly stable.