Dear Fellow Brickboarders,

Hope you're well. For the B230FD engine, a thermostat that opens at 92°C (198°F) is specified. For the B230FT engine, a thermostat that opens at 87°C (189°F) is specified.

I presume that such a temperature difference is meaningful.

If an 87°C thermostat were installed in a cooling system for a B230FD engine, what would be the impacts of using an earlier-opening thermostat?

Thanks for your help. I'm much obliged.

Yours faithfully,

Spook

Dear Fellow Brickboarders,

May this find you Well. I replaced the timing belt, rear timing belt case, tensioner, water pump, thermostat and hoses on 94 940 (93K). The water pump top seal extruded and started to leak. The seals were in good shape.

The thermostat - replaced by the former owner's Volvo dealer in 2001 - was an 87°C Wahler unit, marked Volvo 1219675. I replaced it with a Vernet unit, 88°C. I do not expect any impacts from so small a difference.

Volvo VADIS - the now superseded Volvo Dealer parts and maintenance database - offers a choice between the 87°C and 92°C units. I see no reason to allow a heat build-up.

Thanks again for your helpful replies.

Yours faithfully,

Spook

I have a '73 Datsun 240Z track car with an '82 turbo engine and inter-cooler. The information I read suggest running a 160 degree thermo instead of 190 degrees.
The reasoning has to do with the water cooling and oil cooling of the turbo bearing. The lower temperature helps to extend the life of the turbo by slowing down coking of the bearing. Additionally, the lower reflected heat from the radator to the inter-cooler helps reduce the heat of the compressed air flowing into the butterfly valve.

Perhaps this is in the thinking by the Volvo engineers. Even a reduction of 10 degrees would be helpful for a turbo engine.

I got a stat from the dealer a while back for the 940 (B230FD), and they handed me a 92C Wahler - with "Volvo" stamped into the rim.

In my 83 240 with a true temperature gauge, I see a little less than a needle's width difference between the 87 and 92 stats at full operating temp. In the family fleet, all red blocks run the 92.

Benefits? in general the hotter stat should give a bit better efficiency in terms of fuel economy and emissions. It also should 'burn off' condensation inside the engine a bit faster and more completely, and this could be important if frequent short trips are a part of the car's usage pattern.

I doubt the 92C stat would bring greater risk of overheating, as a properly sealed cooling system with 50/50 antifreeze won't boil until about 125C with the 150kPa 940 reservoir cap. (In the GM factory books for my LT-1 powered 740, the electric fans' low-speed trip is at 108C and the high-speed point is 113C)

In my 1989 740 owner's manual, the stats are specified as 92C for Turbo, and 87C for non-turbo cars. Intuitively, that seems backwards. Misprint?
--
Bob (son's 81-244GL B21F-M46, dtr's 94-940 B230FD, my 83-244DL B23F-M46, 89-745(LT1 V8), 98-S90, 77MGB and four old motorcycles)

As far as I know if you order it from the dealer only the 87 degree 'stat is available.

Hi

I use an 87 deg in the summer time, because my car idles a lot and the cooling fan runs enough to annoy me. During the winter months I want extra heat to melt the snow off the windshield, so then I use the 92 deg one.

Not meaningful.