water temp too high?
Thread Starter
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Joined: Jun 2010
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water temp too high?
started my 79 vette for the first time since rebuild ,instead of the temp sensor in the thermostat housing ,I put it in the intake manifold (I wanted a chrome housing) temp gauge reads 220 ,seems hot to me .I put a 195 stat in, should it be this hot all the time? I don't want to blow a new engine
Team Owner
Joined: Jul 2008
Posts: 23,419
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
I would use an IR gun to test the real water temp at the thermostat housing to confirm that you really have 220 degree coolant. If you do, there are a littany of things you can check to see if they are contributing to a high temp reading, including but not limited to:
1. Make sure your system is filled to the proper level with a proper mixture.
2. Make sure your fan housing is in place and in good shape.
3. Check your timing.
4. Make sure your chin spoiler is installed.
5. Make sure your fan clutch is working properly.
All of these are good places to start. Any decent repair manual will have a troubleshooting procedure in it for diagnosing hot coolant, and there have been numerous threads on this over the years with a lot more information than I could include in a single post. If everything on your car checks out, and you are still getting 220 degree coolant, you can either live with it, or change something in the system to get it to run cooler. There are numerous vendors on here that would be glad to help you with that.
1. Make sure your system is filled to the proper level with a proper mixture.
2. Make sure your fan housing is in place and in good shape.
3. Check your timing.
4. Make sure your chin spoiler is installed.
5. Make sure your fan clutch is working properly.
All of these are good places to start. Any decent repair manual will have a troubleshooting procedure in it for diagnosing hot coolant, and there have been numerous threads on this over the years with a lot more information than I could include in a single post. If everything on your car checks out, and you are still getting 220 degree coolant, you can either live with it, or change something in the system to get it to run cooler. There are numerous vendors on here that would be glad to help you with that.
Thread Starter
Advanced
Joined: Jun 2010
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how to check temp
this is my first corvette, in the past when I started an engine I could always leave the cap off to watch the level, when I stated the vette with the cap off it looked like a fountain ,antifreeze gushing out so I put the cap on as fast as I could, new aluminum water pump, I have not replaced the chin spoiler yet ,I was working on other things up front ,how do I check the temp ,just point the ir at the hose ?
Melting Slicks
Joined: Oct 2008
Posts: 2,154
Likes: 69
From: Regina Sk Canada
I just built a new 355 sbc with 9.5-1 compression, dual pattern cam with 20 deg initial timing, 35 total. Stock 3 core rad, that was taken apart and re-rodded so the cores are nice and open. Stock shroud, water pump,and clutch fan. 180 thermostat, plus a 16lb rad cap and we run at 190 degrees in hot stop and go traffic.
I always fill from the thermostat on the intake, that makes sure all the air is forced out.
I always fill from the thermostat on the intake, that makes sure all the air is forced out.
Burning Brakes
Joined: Jun 2005
Posts: 764
Likes: 2
From: THE OLDER I GET THE BETTER I WAS! NORTHERN ONTARIO
Are you using your original sending unit or a replacement from aftermarket...if so It could be that the sender is slightly off mine was off 10 degrees from original. Just a thought
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Drifting
Joined: May 2005
Posts: 1,629
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From: Somers CT
Yeah, something doesn't sound right, that shouldn't happen with a cold engine and the stat closed.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
new alum pump ... gushing on startup ... temps higher than norm.
lotta new alum pumps don't have bypass hole as stock pump does ... without enough bypass, air is easily entrained-trapped. Suggest drill one or 2 small 1/8" holes near edge of thermostat. Do NOT overdo it on holes or you may as well simply discard t'sat. Alternately but only If you really know what you're doing, you might drill alum pump for bypass.
chin spoiler asap
lotta new alum pumps don't have bypass hole as stock pump does ... without enough bypass, air is easily entrained-trapped. Suggest drill one or 2 small 1/8" holes near edge of thermostat. Do NOT overdo it on holes or you may as well simply discard t'sat. Alternately but only If you really know what you're doing, you might drill alum pump for bypass.
chin spoiler asap
Le Mans Master
Joined: Oct 2007
Posts: 7,451
Likes: 974
From: RI, Now Franklin/Nashville TN
Not much to add here except that the 78/79 L-82's routinely ran 220-225 degrees and could go as high as 240 with the OEM cooling system and all the pollution gear. If you are running the original radiator and with a new engine making a lot more HP the cooling system may not be able to keep up. My 78 with the original L-82 has been a battle with coolant temperatures since day one. I finaly solved the problem with a Dewitts aluminum radiator, Stewart stage 2 aluminum water pump, and a robertshaw HP thermostat. Car runs at 180 on the highway now at 95 degrees. Never did previously.
PS Have OEM fan shroud, GM fan clutch, chin spoiler with 79 rubber extension (79's only had this feature), etc.
PS Have OEM fan shroud, GM fan clutch, chin spoiler with 79 rubber extension (79's only had this feature), etc.
Le Mans Master
Joined: Oct 2007
Posts: 7,451
Likes: 974
From: RI, Now Franklin/Nashville TN
Excellent point which I forgot to mention as well. The temp sender is on the driver's side of the block, not in the thermo housing.
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
Not much to add here except that the 78/79 L-82's routinely ran 220-225 degrees and could go as high as 240 with the OEM cooling system and all the pollution gear. If you are running the original radiator and with a new engine making a lot more HP the cooling system may not be able to keep up. My 78 with the original L-82 has been a battle with coolant temperatures since day one. I finaly solved the problem with a Dewitts aluminum radiator, Stewart stage 2 aluminum water pump, and a robertshaw HP thermostat. Car runs at 180 on the highway now at 95 degrees. Never did previously.
PS Have OEM fan shroud, GM fan clutch, chin spoiler with 79 rubber extension (79's only had this feature), etc.
PS Have OEM fan shroud, GM fan clutch, chin spoiler with 79 rubber extension (79's only had this feature), etc.
Thread Starter
Advanced
Joined: Jun 2010
Posts: 82
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no more 220 degrees
problem solved , I put a 160 thermostat in last night and drove it for an hour in the country and in town stopping at all the lights ,and never got over 180-185 ,my next question is has anyone ever put a 700r4 trans in a 79 vette ,I need to have some overdrive for highway speeds
Race Director
Joined: Sep 2002
Posts: 10,362
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From: San Diego - Deep Within The State of CONFUSION!
started my 79 vette for the first time since rebuild ,instead of the temp sensor in the thermostat housing ,I put it in the intake manifold (I wanted a chrome housing) temp gauge reads 220 ,seems hot to me .I put a 195 stat in, should it be this hot all the time? I don't want to blow a new engine
There is no way for a thermostat to keep an engine from getting HOTTER than the preset temp. That is just not what it is designed to do. Now, if you have a great radiator, proper coolant mixture, etc and you're going downhill on a cool day, the engine temp may go too low, for a minute or so. At this point the t'stat will close a bit to bring the engine back up to the preset temp (this should be 180* minimum)
But that is the ONLY scenario I can think of that would bring the thermostat back into play after it has already opened and the engine is at proper temp. Perhaps opening the heater control valve may introduce enough cool coolant to bring the temp down for a second too, but I doubt it.
