OK, let's recap the problem for those who haven't followed this problem through last summer:

My '64 PV544 with B20 engine and BW35 trans had a bad habit of running hot. At least that's what the original Volvo gauge was telling me. This would happen when idling in traffic or climbing grades.

The Volvo gauges seem to be 'pessimistic' to me; the temp gauge shows the engine running hotter than it does, and the fuel gauge says I have less gas than I actually have.

I boiled out the radiator and refilled with 50/50 ethylene glycol antifreeze, then I installed a 170 degree thermostat. The PO had a 190 installed.

I gained a little ground, but still the gauge would climp to the HOT end while idling in traffic.

Next, I ditched the scrawny 4-blade original Volvo fan for a 6-blade Flex Fan.

This got me through the tail end of last summer, and through the winter (naturally!)

I know that if your ignition timing is reatrded too much it can cause overheating. I checked mine, and it was off a little, but not that much. I set it at 20 degrees BTDC and the car certainly ran better!

This past weekend was relatively hot, temps in the 80's. I drove over to Barstow for a car show (about 93 miles each way) and discovered that unless I was driving into the wind, the gauge would go right up to HOT again.

Turn the car so it was moving even slightly into the wind, and the temp would drop immediately.

There are two more steps I can take: One would be to install the fan shroud I started to make last summer, and the other would be to buy and install a pair of electric fans on the front of the radiator.

I just came back from the parts store, where I got a jug of Water Wetter, which is supposed to increase the heat transfer ability of your coolant. I'll drive with that in the system for a few days and see what it does.

Any thoughts or suggestions?

Steve

I have a freind who had one of the 60's Dodge cab over pickups and put a 1000HP (no mis-print) Chrysler Hemi right behind the cab + nitrous. Monster engine-- and Evans coolant solved his overheating problem. No thermostat and NO water. This was a couple years back and I rode with him in the truck in a parade in the summer and the engine never got above 160 degrees. He says it eliminates the nucleate boiling that occures around the cylinder walls in the cooling channels. Back then it cost $50 for 1 gallon. Might be worth the investment.

I don't see any mention of the car actually getting hot. If by now, you have not actually lost coolant (boiled over), I would recalibrate the temp guage (in my head) and move on.

Gary L
--
1971 142E ITB racer, 1973 1800ES, 2002 S60 T5

You're right, of curse. Just because the temp gauge needle goes to the HOT peg and stays there doesn't mean the engine is actually running hot. Every Volvo temp gauge I've tried ran hot. I have a 'spare' aftermarket temp gauge I can just screw into the head and hang under the dash until I get a feeling for what the engine is actually doing.

I see JC Whitney has a radiator cap with a built-in temp gauge. One of those might be handy as a way to double-check the accuracy of the dash gauge.

The Volvo gauge isn't all that hard to recalibrate. I'll need to know how far off it is by comparing its reading to the other gauge, then I can adjust the air chember diameter so it coincides with it.

I found an article last year about a guy with a buddy and his big block PV and wrote about the coolant used. The car kept in the middle range of temps when they were cruzn' in the middle of a Hot day.
http://www.evanscooling.com/html/msports1.htm Evens was the coolant and the original radiator was inplace. I did't keep the article but checked into the coolant. You have to use their stuff and not a drop of anything else. You may know about it but it was new to me.
Here is another auto board discussing Evens merits. http://forums.tccoa.com/showthread.php?t=50751
Zero in on the thoughts about keeping the coolant on the cylinder walls.
Keith

I've never heard if Evans out here, but we have Water Wetter, which appears to be a similar product. It increases the ability of your coolant to transfer heat, making the cooling system work more efficiently. Unfortunately Water Wetter costs a LOT, so I'll do other, less drastic things until I'm satisfied.

I'm trying a product from NAPA that claims to be the same stuff. When I opened the can it was clear, very thin, and smelled a little like kerosene. I'll see what that stuff does on the next warm afternoon.

The thing that strikes me is that you are using an uncalibrated forty-year-old gauge to base your assumptions. What do you think of pointing one of those laser infrared thermometer thingies at your block, radiator, hoses, etc when the gauge is showing hot. Perhaps there is not nor has there ever been anything wrong with your cooling system other than your gauge is 30F off.
--
Volvo Farmer:

21 Volvos '58-'91

445-544-122-144-1800-240-740

sorry, no FWD

Steve:

Do you have an OEM t'stat in there? I had overheating problems with a couple of aftermarket t'stats. After installing a t'stat purchased direct from a Volvo dealer the overheating stopped.

I also noticed that the cooling system was extremely sensitive to low coolant level. A cup short would cause havoc.

Best regards,

Joe M in WV

It's a non-Volvo thermostat, but it isn't restricting the full flow of coolant. I checked that in the house, using the pot of water and thermometer system. :-)

The radiator only spits up about 1/3 cup of coolant into the return tank, so obviously it's not running as hot as it says it is.

I think I will install that aftermarket gauge today and go for a drive in the mountains - or out across Death Valley.

Then again, maybe I'll just drive downtown and find a traffic jam!

I have 3 Volvo temp gauges on hand, and they all read approximately the same. I think I can afford to attempt a recalibration on one of them!

Steve

Hi Steve,

If you do decide to fit electric cooling fans, you might need to have a think about their positioning. I've spoken to people who fitted them to Triumph GT6 cars (the GT6 can overheat easily in hot conditions). The consensus was that a better result was gained by positioning the fan behind the radiator so that it drew in air rather than blew air through from the front. It was thought that this maximised the frontal area of the radiator rather than blocking it with fan motors etc. I know that most modern cars have the fan fitted in front of the radiator but the cooling requirements of modern cars seem to be quite different to the older cast iron blocks. Mind you, the cooling requirements of older Triumphs may be different as well!

Aidan
--
1967 131, 1969 131, 1973 Triumph GT6, 1972 Triumph Spitfire 2.5

Rear fans(pullers) are generally better to use, and it's always BEST to use them with a fan shroud. That being said, a large pusher up front that does a good job of flowing air, is more than adequate for a Volvo of this vintage usually(unless you turbocharge it).

I vote mainly guage bluff Steve, but we shall see! I wish you the best of luck!