Date: Sun, 2 Jan 2000
Hi Glenn,
I have a substantial amount of oil in the coolant of my stock P. I have the head off, and the gasket appeared fine, and the head and block check out without any warping. My mechanic believes that the mixture of oil and water may be originating in the oil cooler. Any ideas on a good way to confirm that diagnosis? He believes he should disconnect the water lines to the cooler and observe the cooler to see if oil passes out as the engine runs. My fear of course is that I have a problem in the block, so I am hoping that the cooler is the culprit.
Is the cooler available? Have they been subject to problems in your experience? I work on the car myself to a certain extent, but in this case I have taken the car to IWARS in Dallas, as he has proven to be a great guy who also appreciates the P, although he does not specialize in the breed.
This is my daily driver (no commute as I work at home), so any help will be doubly appreciated. I can't tell you how much I enjoy this car (light green and really original, my pride and joy).
Chuck in FairPark, Dallas.
Hi, Chuck - Good to hear from a local enthusiast. Yes, I believe the oil cooler is the most likely culprit. It is extremely unlikely that anything inside the engine block could introduce oil into the coolant. Most 1800s are missing the oil cooler now, as they do wear out eventually, and replacements are not being manufactured.
Your mechanic's idea for testing sounds valid to me. Another way would be to remove the oil cooler, apply air pressure to the coolant ports, and listen for escaping air in the oil ports. Although I have never removed a cooler myself, I believe it is a fairly simple process. Once you have the cooler out, the oil filter will attach directly to the block if you replace the oil filter screw pipe with one from a non-cooler B-18 or B-20 block. You'll also need a blanking plate for the water return hole in the head, and of course you'll have to replace the bottom radiator hose with a simple right-angle hose from your local auto supply.
If I knew where you could buy a new stock oil cooler, I'd say replace it, but given that the condition of a used cooler could not be much better than yours, I'm afraid the best option is to do without. -Glenn.
For those who may never have seen one, the stock oil cooler was fitted to early and mid-production P1800s. It is a fat disc-shaped object, about a foot in diameter, located where the oil filter would be on other Volvo models. The oil filter on oil cooler-equipped P1800s screws onto the middle of the oil cooler. The cooler works by circulating engine coolant and oil in adjacent passageways. Heat from the oil is picked up by the coolant and dissipated in the radiator. Coolant is supplied from a long extension of the bottom radiator hose and returned via a pipe to a port near the front of the cylinder head. -Glenn.