In the process of trying to fix the oil leak at radiator / oil cooler lines, I started the car cold and I got sprayed with cold oil everywhere. I understand the oil thermostat is supposed to let some oil through (10% I think) to maintain pressure, but I think there was a lot more. So I am assuming the oil thermostat is not doing its job -- close the oil flow to the Cooler until oil reaches certain temperature (I think 175 degrees F). If the thermostat is not doing its job, this is not good, especially in cold months.

I looked at IPD, FCP and Advance Auto parts and no one seems to carry this oil thermostat. I plan to take out the thermostat tomorrow and connect lines in and out so no oil goes to the Cooler until I replace the thermostat and lines.

Is there a sure way to fix the oil thermostat? If not, does anybody know where to buy it?

The oil cooler feature is nice, but hoses are a nightmare for leaks. I fixed one, but still working on the 2nd one. By the way, the prices for these Volvo hoses are really ridiculous, and they leak. Meanwhile, I usually spend $ 10 in hoses when I install an aftermarket transmission cooler typically.

I am leaning towards buying an aftermarket oil thermostat and replacing the hoses with regular transmission oil cooler hoses. Any critics?

 

Link to aftermarket oil thermostat... http://www.racerpartswholesale.com/p...il_Thermostats

 

I looked at the oil thermostat today. This thing is not connected to the oil pan by lines, it actually bolted directly onto it. Then lines run from the thermostat up to the cooler. Does anybody know if nipples can be connected to the 2 ports on the pan?

I did not take it out since I did not have the gaskets Thermostat-to-pan.

 

I cut the steel lines post-thermostat and connected them to each-other with a rubber hose, i.e. oil cooler is not used. This is a temporary solution. I am looking into the correct piping/hoses and fittings, since I will no longer use Volvo OEM lines.

According to Volvo literature oil pressure is minimum 14 psi at idle and maximum is 43 psi at 3000 rpm. This is the same for 850 NA and Turbo ('95-96); again I have both 2.4 and 2.3 Engine Volvo's documents and pressures are the same. However, I understand that the lubrication system for Turbo is different from NA, and the oil pumps are different Part Numbers (at FCP). Maybe someone can explain this?

From other research I have learned that 850 Turbo oil pump's capacity has been increased by a wider pump wheel and a modified profile. Yet, Volvo documents show that both pumps push the same psi pressure.

Regarding Oil Thermostat: it starts to open at 203 degree F oil temperature and is fully open at 300 degrees F oil temperature.

Transmission cooler hoses would work. They are rated from 150 to 300 psi, depending on quality. However, the biggest size Auto Parts stores (NAPA, Autozone, Advance) stock are 3/8", when the steel lines I cut were 1/2". I could force this hose such into the steel line, but I would like to get at least 1" of coverage and 2 worm-clamps. The temporary hose I have installed is GoodYear 1/2" fuel injection hose (rated for 35 psi max), which is the only one I could find around (NAPA). The shop owner who did the job yesterday said "it should be no problem", but I told him that I am skeptical, even for a temporary hose, until the weekend. We'll see.

Fittings: 2 Nipples (3/8" male thread / ****** end) will be needed to connect hoses at the cooler/radiator.

I was also looking hydrolic / fittings at www.discounthydrolichose.com. These are rated for 2000 psi or so. The only issue with the hose is if it can be routed (1/2" hydrolic hose requires minimum 7" bend). Total cost 8 feet hose + fittings was $ 15, plus $ 10 shipping.

 

Well. I found the 1/2" (ID, inside diameter) hose at NAPA today, Strangely the NAPA guy pulled it out of a Transmission cooler kit and sold it to me for $ 3.99 per foot. This Gates hose is rated for 400 psi. I found the fittings at Ace Hardware, at $ 4.29 each x 2. These are brass adapters -- male threads to ****** ends. Rated for 400 psi too. These fittings might be different for different radiators (I know the old / busted radiator used different size fittings).

Thermostat remains suspect, but I will not have time to check it this weekend. I gotta to do the hoses first, since the temporary ones is rated for 35 psi max, and have been driving this thing easy, not exceeding 2200-2300 rpms.

 

Got it finished today. The most difficult task was to remove the single 10 mm bolt holding the bracket of both engine cooler lined into the block. 10 minutes with a 3/8" universal joint got it out.

I used yellow teflon for threads (male fittings into radiator/cooler female port). This yellow teflon is the not the same as the white one. The yellow one is rated for high-pressure, high-temperature, petroleum products, etc etc. I used double-worms where rubber hose is connected to the OEM steel lines.

Drove 100 miles -- no more leaks under the car finally. I will be opening the thermostat at another time -- had a BDay party to go to today.

These 1/2" Gates rubber lines may not last 15 years like the OEM ones, but there are easy to repair / replace. I should be OK for the next 5-7 years.