Engine slowly overheats. Causes?
Thread Starter
10 Second Club
iTrader: (1)
Joined: Mar 2002
Posts: 1,088
Likes: 0
From: St.Louis, MO
Engine slowly overheats. Causes? The fans work (high and low), coolant level is completely full and I'm not losing any coolant, nothing is blocking the radiator. I am using Evans coolant and I have a Mezzier Elec water pump and a 160* thermostat.
After driving on the highway for about 15 minutes the temp gauge sloooooowly climbs to 210, then it jumps to 230+. I let off the gas and slow down and it falls back to around 210 or so. As long as I drive under 50 mph it stays around 210.
This just started happening. My gauge always read well below 210. All I can think of is a bad thermostat or my electric water pump is going bad. Any other ideas?
After driving on the highway for about 15 minutes the temp gauge sloooooowly climbs to 210, then it jumps to 230+. I let off the gas and slow down and it falls back to around 210 or so. As long as I drive under 50 mph it stays around 210.
This just started happening. My gauge always read well below 210. All I can think of is a bad thermostat or my electric water pump is going bad. Any other ideas?
TECH Senior Member
iTrader: (3)
Joined: Apr 2006
Posts: 6,524
Likes: 1
From: Western Burbs of Detroit
I too have a Meziere. Make sure none of your electrical connections are loose. You may have a pump that working intermittently.
I agree with the above, make sure your air dam is intact. If it isn't then adequate air isn't being routed over the radiator at higher speeds (more rpms, more heat).
I agree with the above, make sure your air dam is intact. If it isn't then adequate air isn't being routed over the radiator at higher speeds (more rpms, more heat).
TECH Resident
Joined: Aug 2003
Posts: 970
Likes: 4
From: England UK
I would check the thermostat. Perhaps the water pump.
Highway driving should cool the car down, more air under the car cools the engine, if I'm slowly driving around town the fans will come on, bay neve ron the highway. I too have the 160* stat, had no problem, my gauge always sits below half way.
Another thing to check is O2 switching, i know it sounds crazy at first, but if you are running too lean, then it will get hotter. Its just another thing to check if you can.
Highway driving should cool the car down, more air under the car cools the engine, if I'm slowly driving around town the fans will come on, bay neve ron the highway. I too have the 160* stat, had no problem, my gauge always sits below half way.
Another thing to check is O2 switching, i know it sounds crazy at first, but if you are running too lean, then it will get hotter. Its just another thing to check if you can.
Thread Starter
10 Second Club
iTrader: (1)
Joined: Mar 2002
Posts: 1,088
Likes: 0
From: St.Louis, MO
I know I'm not running lean. I have a LC1 wideband. Stays around 14:1 on the highway. That's fine for part throttle.
This started after a heads/cam install. We also installed a double roller timing chain and I also deleted my PCV and installed breathers on both valve covers. I don't know why any of these things would cause my problem though.
This started after a heads/cam install. We also installed a double roller timing chain and I also deleted my PCV and installed breathers on both valve covers. I don't know why any of these things would cause my problem though.
TECH Resident
Joined: Aug 2003
Posts: 970
Likes: 4
From: England UK
There are 4 coolant pipes for the heads, are these okay, are they like stock?
I've plugged my rear ones, the front ones are required to link to each other and run to the rad.
Perhaps you still have some air in the coolant system. Run it on tick over with the rad cap off, perhaps squeeze some of them large water pipes, watch out that you don't get caught in the fan.
I don't have any experience in the electric pump, perhaps 'allngn_c5' has a valid comment.
I've plugged my rear ones, the front ones are required to link to each other and run to the rad.
Perhaps you still have some air in the coolant system. Run it on tick over with the rad cap off, perhaps squeeze some of them large water pipes, watch out that you don't get caught in the fan.
I don't have any experience in the electric pump, perhaps 'allngn_c5' has a valid comment.
Originally Posted by PewterZ28
After driving on the highway for about 15 minutes the temp gauge sloooooowly climbs to 210, then it jumps to 230+. I let off the gas and slow down and it falls back to around 210 or so. As long as I drive under 50 mph it stays around 210.
Are you talking like the temp drops in a matter of seconds after slowing down?
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo TECH Senior Member
iTrader: (3)
Joined: Apr 2006
Posts: 6,524
Likes: 1
From: Western Burbs of Detroit
Originally Posted by RedWS6 00
I don't have any experience in the electric pump, perhaps 'allngn_c5' has a valid comment.
Check all connections, and even check the fuse for your Meziere, you may be maintaining engine temp soley with the cooling fans if your fuse is blown. Do you hear the electric motor of the Meziere when you turn the key to on? I could be wrong. Ask one of the local performance shops. They will have a better idea.
Thread Starter
10 Second Club
iTrader: (1)
Joined: Mar 2002
Posts: 1,088
Likes: 0
From: St.Louis, MO
The pump definitely comes on when I turn the key on.
Yep. Like I said, it slooooowly climbs to 210 (takes like 5 or 10 minutes), then it takes another couple minutes to go a hair past 210, then in a matter of 1 or 2 seconds it shoots up to 230+, then as soon as I let off the gas and slow down to 45 or slower the temp falls back to 210 in a matter of 2 or 3 seconds. As long as I go slower than 50 it stays at 210 or 215.
My mechanic is stumped. So am I.
Originally Posted by dhdenney
Are you talking like the temp drops in a matter of seconds after slowing down?
My mechanic is stumped. So am I.
Originally Posted by PewterZ28
The pump definitely comes on when I turn the key on.
Yep. Like I said, it slooooowly climbs to 210 (takes like 5 or 10 minutes), then it takes another couple minutes to go a hair past 210, then in a matter of 1 or 2 seconds it shoots up to 230+, then as soon as I let off the gas and slow down to 45 or slower the temp falls back to 210 in a matter of 2 or 3 seconds. As long as I go slower than 50 it stays at 210 or 215.
My mechanic is stumped. So am I.
Yep. Like I said, it slooooowly climbs to 210 (takes like 5 or 10 minutes), then it takes another couple minutes to go a hair past 210, then in a matter of 1 or 2 seconds it shoots up to 230+, then as soon as I let off the gas and slow down to 45 or slower the temp falls back to 210 in a matter of 2 or 3 seconds. As long as I go slower than 50 it stays at 210 or 215.
My mechanic is stumped. So am I.
There's no way heat could be removed from the engine that fast. I think you've got an electrical problem. I'd be checking the sensor/sender and the gauge cluster. I had a fan problem on my LT1 once and it would cool fine out on the highway but as soon as I started stop and go traffic, it would start climbing. Get back on the highway, the engine would only cool maybe 5-10 degrees even though it climbed 50 in traffic. The one fan running and the electric pump moving and all the airflow at 60 mph could not cool it back down. It would stop it from getting hotter, but it couldn't cool it. I put my laptop on it when I got home and with the car off and electric pump on, it would only cool a couple of degrees every 2-3 mins. So I am fairly confident that your car cannot cool 25 degrees in 2-3 seconds.
Thread Starter
10 Second Club
iTrader: (1)
Joined: Mar 2002
Posts: 1,088
Likes: 0
From: St.Louis, MO
I don't know about that. If coolant were to suddenly stop flowing and then start again that could cause a rapid climb and even fall in temperature. This has happend 3 times now. Same thing every time. It takes about 15 or 20 minutes of highway driving with temps rising about 1 degree every minute. Then when engine temp gets up to about 215 the gauge climbs to 230+ in a matter of 1 or 2 seconds. I let off the gas and the temps fall back to 215 or 210. My car always ran 180 to 190 degrees prior to this problem. So even 210 is very high for my car.
Just a though.. have you check your radiator...? plugged ?.. (dexcool), maybe flush the system and refill and make sure you get all of the air out of the system.. fill the engine directly in from the top radiator hose.. then reconnect and finish filling the system.
Originally Posted by PewterZ28
I don't know about that. If coolant were to suddenly stop flowing and then start again that could cause a rapid climb and even fall in temperature. This has happend 3 times now. Same thing every time. It takes about 15 or 20 minutes of highway driving with temps rising about 1 degree every minute. Then when engine temp gets up to about 215 the gauge climbs to 230+ in a matter of 1 or 2 seconds. I let off the gas and the temps fall back to 215 or 210. My car always ran 180 to 190 degrees prior to this problem. So even 210 is very high for my car.
12 Second Club
iTrader: (13)
Joined: Feb 2005
Posts: 1,575
Likes: 1
From: Gateway International Raceway
Do you have a scanner...the guage is wrong or should I say off. My car runs at 192 or 193 and the guage says 210. I check mine with HPTuners and I think maybe your thermostat is sticking or you have one or both of your head gaskets occluding some water holes...as speed/load increases the engine is producing more heat and limited flow like that will make the engine heat up and when you let off it will cool.
Just my $0.02
Just my $0.02
Thread Starter
10 Second Club
iTrader: (1)
Joined: Mar 2002
Posts: 1,088
Likes: 0
From: St.Louis, MO
Originally Posted by ExceSSive
Do you have a scanner...the guage is wrong or should I say off. My car runs at 192 or 193 and the guage says 210. I check mine with HPTuners and I think maybe your thermostat is sticking or you have one or both of your head gaskets occluding some water holes...as speed/load increases the engine is producing more heat and limited flow like that will make the engine heat up and when you let off it will cool.
Just my $0.02
Just my $0.02
The head gaskets are .040 Cometic. I'd be surprised if they were not designed right.
Last edited by PewterZ28; May 1, 2007 at 12:24 PM.
TECH Fanatic
Joined: Mar 2004
Posts: 1,017
Likes: 0
From: Laguna Niguel, CA
My car started to run hot one day out of the blue, for NO reason at all. My car normally runs ~185 (1998 working gauge here) with my manual fan switch on ALL the time. It started to run up about 200 and then 210 and I thought for sure that the fans were not working properly.
I thought to myself "I might change the T-stat and coolant first" and sure enough, the car started running back at normal 185 again...
I thought to myself "I might change the T-stat and coolant first" and sure enough, the car started running back at normal 185 again...