Quick question from a newbie

[skelly]

I bought my '64 Sprite a couple of weeks ago and noticed the coolant temp got a bit high (195) on an extended drive. At the same time my oil pressure dropped fairly low (under 20). I installed a summer thermostat rated at 160 degrees to bring the temp down. The thermostat that came out was a 180 degree one. After installing the summer thermostat the gauge now reads 180 degrees after warm-up . Is it possible for the water temp gauge to read 20 degrees high? BTW, I changed the oil to Valvoline VR-1 20W-50 and my oil pressure stays at or above 40. Can the water temp gauge be calibrated? Thanks for the help.

 

[RickB]

How was the weather? If it was cold out then I would take a look at the radiator.
If it was hot then I'd say 195 really is pretty good.
I've got a 190 thermostat since I drive in cold wet a lot of the time and I want my heater to get as hot as possible. That's in my Midget

However in my MK2 Sprite the temp stays about 190 IIRC.

 

[nomad]

Part of the fun of just about any british car! Least by my experience, they tend to run a bit on the warm side. I would say your temp readings are accurate. Just keep an eye on it and if it gets close to boiling you may want to back off the throttle a bit. Either that or look to changing radiators. There are a few things to watch for. First is your ignition timing right? Carb setting pretty close?
A electric fan will probably help keep things cooler in city traffic since the early fan shroud dosn't do that great a job. If you want to do more, like change radiators, there are options this group will be happy to help with.

I believe Barney Gaylords "MGA Guru" site suggests you put a piece of tape over the guage if it really bothers you!!! (My MGA is terrible for running hot but then it needs the block cooked out as well!)

Kurt.

 

[skelly]

It was about 90 and I was running at highway speed. The temp dropped a bit once I slowed down. I'll keep an eye on things but the new thermostat lets it run lots cooler. I do need to put a piece of tape over my tach. It is way off. Drives me crazy looking at it. It will be fun to get things all sorted out with this car. Thanks for your comments.

 

[JPSmit]

And, if your oil pressure is below 20 at speed, there is probably a rebuild in your future. For now, you might want to add a litre of Lucas oil additive. I do and it boosted my pressure just enough!

 

[bthompson]

That's true. Under 20psi at hot idle is normal, but with any RPM at all your oil should be above 40. If it stays low, odds are that the bearings need refreshing.

If you want a quick-and-dirty way to check your temp gauge, just pull the sensor bulb out and plunk it in a mug of boiling water with a candy thermometer in it. Keep an eye on the gauge and the thermometer as the mug of water cools off, and see where the gauge sits at every, say, 10 degrees. That'll give you a good idea just where your temp really is.

 

[DRH]

For the desert guys, most DIYers go for the 160 degree thermostat. But that doesn't mean you're going to get 160 degrees on your temp gauge in any summer. What that means is the valve opens at 160. The warmth of the day may still give you 185 degrees....or 200 degrees plus in the engine. In order to compare the thermostat against the temp gauge, you need to make the test in the cold of winter. That way, the engine is operating at its lowest temp that the thermostat allows and the temp gauge should reflect that. If it's not boiling over, it's probably just fine.

 

[Pythias]

195 degrees at high speed on a 90 degree day is not bad at all, especially if you have your heater valve closed off.

 

[bug_sixty]

Heh Bill that's not a problem we have very often is it...90+ degree days

 

[Pythias]

About 4 years ago though, I was stuck in a Seattle traffic jam, blocks long, (mariners game) late July. The ambient temp was 95 degrees or hotter and the car never went over 205 degrees. This is without an oil cooler, as Paul A. made me take it out when he rebuilt the engine. He maintained that 1)the cars don't need it, and 2)I would never be able to get all the oil out on when I changed oil, so I would ALWAYS be running dirty oil. Instead I had the radiator re-cored and have never had a heating issue, though this IS the PAC-Northwest.

 

[skelly]

After switching to a 160 degree thermostat, I did a fairly long drive at highway speeds and the coolant temp kept rising to 200 degrees and over. Yikes! I want to be able to drive this car anywhere so I decided to install a new radiator. I also put the 180 degree thermostat back in so I can have some heat in cooler weather. Before I filled the system with antifreeze, I tried the hot water and candy thermometer check of the temp gauge. It read 5 degrees high from 200 down to 170. After filling the new radiator and running to operating temp, I topped it off and went for a long highway drive with air temp of 90 degrees. The temp gauge rose to 190 and stayed put. After taking into account it reads 5 degrees high, that makes it running at 185 degrees both city and highway. I also installed the six blade plastic fan. Hope these changes allow it to operate at a temp that I feel safe with. Thanks for all your suggestions.

Jay