LT1-LT4 Modifications 1993-97 Gen II Small Block V8

weird overheating issue...

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Old Jun 6, 2009 | 09:13 PM
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Default weird overheating issue...

okay its a 96 formula.. new waterpump.. fans are working fine

I recently moved from knoxville, tn to east of chicago .. about a 500 mile trip.. made it about 460 miles and my check gauges light comes on the temp was at 240.. the whole trip it was b/t 160 and 190 never any higher..


so i get it towed the rest of the way.. it is parked for a few hours.. i get in it to see whats going on.. start it up and runs fine.. temp stays where it is normally (160-190*) been driving it for a week with only one other occasion of it getting any hotter (just to 210* after 30 minutes of being stopped in a construction zone)

its a mechanical waterpump still all my mods are lt4 hotcam springs, 1.5 rockers, cc502 cam, longtube headers, k&n cai, 3.73 gears, stock stall, shift kit , off road x pipe to two summit mufflers... i think thats all.. i bought the car with the headers on it already.. not sure what thermostat is in it.. me being lazy and skipping things i did not change the thermostat when the waterpump was changed

i figure it has to be the thermostat just wanted to know everybodys opinions on it..
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Old Jun 7, 2009 | 03:53 AM
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I can think of a couple things here.

1 is if you removed the radiator when you did the wp, which you likely did, make SURE everything is hooked back up correctly. I had a really strange overheating/puking issue and I thought it was a blown hg but turned out to be the 2 small hoses near the filler neck of the radiator were reversed and pressurizing the coolant bottle.

That or if your waterpump was a reman there have been those that have had the impeller slipping on the shaft, even on a "new" reman.

I would pop the cover off the front of the wp and verify that isn't happening.
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Old Jun 7, 2009 | 03:54 AM
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3rd thing I forgot that so often gets overlooked with lt1 noobs is to make sure the system is properly bled....
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Old Jun 7, 2009 | 01:41 PM
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Originally Posted by gregrob
3rd thing I forgot that so often gets overlooked with lt1 noobs is to make sure the system is properly bled....
yah the system is bled and everything appears to be hooked up right but it is one of the reman. waterpumps.. ill take a look at it when i get all my tools up here.. not sure what good a screwdriver and 3 odd sized wrenches can do lol..
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Old Jun 7, 2009 | 02:20 PM
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Originally Posted by gregrob
I can think of a couple things here.

1 is if you removed the radiator when you did the wp, which you likely did, make SURE everything is hooked back up correctly. I had a really strange overheating/puking issue and I thought it was a blown hg but turned out to be the 2 small hoses near the filler neck of the radiator were reversed and pressurizing the coolant bottle.

That or if your waterpump was a reman there have been those that have had the impeller slipping on the shaft, even on a "new" reman.

I would pop the cover off the front of the wp and verify that isn't happening.
I had the exact same thing happen to me, it was pretty frustrating. Car will run fine for a few mintues, and then start to puke coolant everywhere.

To the OP....when I am cruising in my M6 car on the highway, if I put it in 6th it will run at about 1200rpm and the temp goes way up around 220 or so. If I drop it down to 5th, the rpm climbs to near 2000rpm and the temp goes down to about 180-190ish. I am thinking I have a weak water pump, and it needs the extra rpm to do it's job. Try to get your car to run hot again around town, but this time leave it in "D" instead of "OD" and see if it helps.
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Old Jun 7, 2009 | 02:44 PM
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Originally Posted by kenscivic
okay its a 96 formula.. new waterpump.. fans are working fine
Did you keep track of how much coolant you drained compared to how much you put in? Usually if you don't drain the block and drain coolant from the w/p jackets you need to put approx 2 gallons back in.

jolester if your system is burping out like that then most likely you have air somewhere in the system.
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Old Jun 7, 2009 | 03:12 PM
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Originally Posted by SS RRR
Did you keep track of how much coolant you drained compared to how much you put in? Usually if you don't drain the block and drain coolant from the w/p jackets you need to put approx 2 gallons back in.

jolester if your system is burping out like that then most likely you have air somewhere in the system.
Nope. It had a little air, but the 2 tiny lines that go into the top of the radiator by the cap were installed wrong. It is very important to install them correctly. I had them swapped by mistake. Once I corrected them everything worked fine, just had to bleed it for a day here and there.
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Old Jun 7, 2009 | 04:38 PM
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Originally Posted by joelster
Nope. It had a little air, but the 2 tiny lines that go into the top of the radiator by the cap were installed wrong. It is very important to install them correctly. I had them swapped by mistake. Once I corrected them everything worked fine, just had to bleed it for a day here and there.
Right... Didn't follow the bold print. One of those lines is a steam return and the other is for the reservoir. So yeah, putting pressure on the radiator cap and into the reservoir tank could do a number...
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Old Jun 20, 2009 | 08:37 PM
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okay sorry for lack of update... all fuses are good, fans are working, system has been bled perfectly...


it only overheats when the car is below 1500 rpms... above 1500 rpms it cools down quick... so i guess it is the reman waterpump
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Old Jun 20, 2009 | 08:56 PM
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Have you replaced the thermostat yet? Maybe it is going out and stopped opening completely, or something...also make sure the air dam is good...maybe its not getting enough air into the radiator...
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Old Jun 20, 2009 | 10:50 PM
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Originally Posted by Z28Camaro30Ann
Have you replaced the thermostat yet? Maybe it is going out and stopped opening completely, or something...also make sure the air dam is good...maybe its not getting enough air into the radiator...
I would change the thermostat first. If I have problem I check to make sure everything is hooked up right than if that doesnt solve it I start with the cheapest and most logical thing first. Might sound stupid but it works good for me.........
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Old Jun 21, 2009 | 09:44 AM
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Originally Posted by Noah's95z28
I would change the thermostat first. If I have problem I check to make sure everything is hooked up right than if that doesnt solve it I start with the cheapest and most logical thing first. Might sound stupid but it works good for me.........
Thermostst x2
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Old Jun 21, 2009 | 11:49 AM
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thermostat changed out, let it idle for a bit, all i could get my hands on was a 180* and its tuned for 160* but im sure that wont **** anything huge up lol.... but ya i rev'd it to about 2 grand for about 8 minutes it stayed under the 190* mark so hopefully that fixed it...
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Old Jun 22, 2009 | 01:03 PM
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well an 8 hour trip turned into a 12 hour trip ... was not the thermostat...
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