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GSXReHab

Probationary Member
8
0
Feb 13, 2012
Baton Rouge, Louisiana
Rebuilt motor with forge internals but used factory crank cause I heard they were a beast. Was this a good idea? More importantly; Also new rebuilt motor has only 40 miles on it. Been trying to break the engine in but motor is overheating. I never let the gauge get into the red but all the water is boiling out of the overflow first. I changed the thermostat (I could see it was broken when removed). But that didn't fix the problem, unless the brand new one broke too?, hadnt checked that yet. It wll idle all day and never get hot. Both radiator fans come on like they are supposed to and I can see the water circulating. Then I go for a ride and it gets hot. Is it just the friction from the new engine or something? I've been breaking it in but not ever going past 5k RPM, running it but not killing it. New oil looks great, no water. My project cant progress until I fix this and I'm pulling my hair out. This happen to anyone else
 
Have you bled the coolant system of air? Air can cause the syptoms you are having.
 
The overheating issue is of great concern if the motor is still new and you have already swapped out the thermostat.
Bleed the cooling system by taking off radiator cap and Start the car when cold and turn on your heater on high, and fill with coolant mixture and your overflow bottle as well. Allow car to idle and wait until you see bubbles, usually until your fans need to kick in. By running your heater, the heater core might fill as well so just top off as necessary until you do not see bubbles and screw on radiator cap .

Try also doing a compression test to see the health of this new motor and as DSMDEMON93 said it is possible head was not torqued down properly with torque spec and pattern. I hope that head was not previously warped from overheating.:pray:
 
I say plus 1 on the bleeding issue...if you don't bleed the cooling system it will cause the problems you are having.puting water in the radiator ig not enough,allthough the water going into the overflow tank on SOME cars is a sign of a blown headgasket or not being torqued right.
 
I say plus 1 on the bleeding issue...if you don't bleed the cooling system it will cause the problems you are having.puting water in the radiator ig not enough,allthough the water going into the overflow tank on SOME cars is a sign of a blown headgasket or not being torqued right.

Plus 2 on this. We all pray your head gasket was not reused and everything was torqued right:pray: Also how is your radiator cap? Typically that is a number one issue of overheating. I have never heard of water going into the over flow as a bad sign but im not gonna rule it out either.
 
Is the water pump new? Are there any leaks..Do a compression test to make sure the head is good...Agreed on bleeding the system.. and there is no such thing as breaking in an engine.. if everything in a rebuilt is done right it should work like a normal car.... "breaking in an engine" to me is to letting the piston rings set, but that depends on what rings you use..
 
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The simple thing for you to do first is replaced the radiator cap, bleed the system again and drive it around to see if it still overheat. A bad radiator cap will also cause it to overheat while your driving.
 
i have a huge fmic and only one fan and ive never had any overheating issues so i would rule out that. if the motor was rebuild due to a bad headgasket then perhaps the radiator got clogged with the milky sludge that resulted from the oil and coolant mixing. air in the system will also result in a false overheating issue because it tends to collect right at the neck where the sensor is..

to check for a clogged radiator i would get the car warm and feel around on the radiator. if the bottom or top feels abnormally cool then you have some clogged tubes.. also plus 1 on the radiator cap.. if your coolant hoses dont feel like they have any pressure in them then thats why..
 
First I want to say I appreciate everybodies replies. I'll try the new cap and bleeding the system, cause that would be easy, but I'm thinking its gotta be the head gasket, cause i've done most of that. Its a new gasket with arp studs torqued to spec by a Haines Manual diagram but Everything else seems fine. We'll see.:banghead:
 
First things first, bleed the system. Jack up the front of the vehicle (and support on stands, chock rear wheels, etc), remove radiator cap, put heat on full blast. start car, let idle until all bubbles are gone.

If you're still having overheating issues after this, and coolant is still being pushed out of the overflow tank, I strongly recommend doing a block leak test to see if you're getting combustion gasses in the cooling system.

If you are, well... time for another tear down...
 
You would definitely know if your HG was no good. Smoke would be bellowing out the tail pipe or your oil would be contaminated with water. Also, you could pull your spark plugs to check for inconsistancies in color or cleanlyness, if one looks different from the rest, you know something different is going on in that cylinder.

A clogged radiator would definitely cause over heating.
A bad radiator cap would let excess coolant flow into the overflow, BUT a blown headgasket will do the same as it will let combustion pressure into the coolant passages forcing coolant out where ever it can go.
 
You would definitely know if your HG was no good. Smoke would be bellowing out the tail pipe or your oil would be contaminated with water

Not always, I've seen a few cases where the head gasket was leaking gasses into the cooling system, but wasn't sucking any in. There was no white smoke.

Also, BHG doesn't always mean that the gasket has ruptured between both the oil AND coolant passages, it can be one or the other. It's more frequent in a lot of vehicles that it blows between both, however.

Either way, just to rule that possibility out, block leak test the system.
 
Get a new cap. My gsx was running hot one day so I shut if off real fast. I poped the hood and checked the radiator cap and the rubber seal was torn bad.. Waited for the car to cool and went to the autoparts store 30 seconds away to get a new cap. it never overheated again once I put the new cap on.
Also I only have one fan workimg and havent overheated because of that. Not saying you don't need it because its there for a reason, just saying.
 
also make sure your engine's under cover (the plastic bit from the front bumper toward the back of the engine bay) is intact. with it missing means that any air coming through the grill will be dumped out before it hits the radiator. sure, air will still be passed through, but not nearly as much as if the cover were in place
 
I have ALL these issues as well.
I have tried everything, bleeding, changing cap, timing belt, thermostat, water pump, put on an MLS and torqued to spec, cleaned out the coolant system.
Still no luck.

Now i also think my radiator is old and clogged.
 
If you think its a clogged radiator try doing a thorough flush. I've had it happen to me before but after I flushed guess what, bad heater core! I flushed out all the debris sealing the heater core as well, LOL. Also +1 on double checking that radiator cap. Maybe its finally time to get that new race radiator you've been dreaming about! Or is that just me?!?!
 
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