car is overheating

[lt1chevelle]

ok so my car is overheating it is running at 220-230 its a 95 lt1 motor. i have bleed the bleeder 3 times and get nothing but water. the expantion tank is at the highest spot and its above the radiator by 2-3in. do you think i need to lower the radiator more?its really starting to frustrate me i cant seem to find the problem.

[alittle1]

Are you looking at the dash gauge? Did you check the water temp with a mechanical gauge? Cooling fan running? Nothing blocking the rad. Is that temp you're getting, running on the hwy? or just sitting in the driveway??

[lt1chevelle]

temp is from a mech gauge not the stock ones, fan is running. and this is the rumbers when i am driving the car

[shep]

I have read that the LT1 is sometimes hard to get burped. Might try parking with the nose up hill over night and try bleeding again. Other than that I got nothing.

[lt1chevelle]

thanks ill give it a try

[paul67]

Have you cured it,does the engine still have the steam lines,is it a side to side flow rad or up and down,does the fan have a cowl around it,are the sides of the rad blocked so the air is forced through the rad and not around when driving,is the thermostate missing if not have you drilled the 1/8" bleed hole in it,are you running A/C,sorry for the long list but these need to be known, I have a 95LT1,in a 67 camaro,I'm using a side to side alloy rad for a big block,level with puke can , no stat but will fit as this can cause air bubbles in the water raising running temp, also run water as this let engine run cooler by about 20f over coolant. This is what I have found out reading mags on said engine.

[BlueBull]

A friend of mine had similar problems a while ago. I'm not sure if this is useful for you but anyhow....

The reason for his problems was the timing. I think the ignition was to late and after adjusted it to correct settings the temperature went down dramatically. I could not even imaging this could happen but it did.

[alittle1]

Did this happen all of a sudden or just over time? Did you make a modification to the car or engine? Let's have some background from you on what took place before.

[megaladon6]

what temp should it be at? that's in it's original car and everything. a lot of GM's in the 90's ran at 210*. i think it started with dex-cool but not too sure. where is the temp sensor located, the stock location or...?

[lt1chevelle]

no i have not solved the problem. and this just started ever since i got the motor back together. the motor is not stock the heads have been ported and polished and has bigger valves. the cam is a gm847 (specs are 590/595) has roller lifters and roller rockers with 37lb ractronix injectors and a holley 52mm tb with long tube headers. the car should be close on its timming i had the comp tuned for the motor but probaly could use a dyno tunning. as for the thermostat being in yes it is its a 160 degree one but i did not drill a hole in it? sorry for the late response i was gone for the weekend

[lt1chevelle]

temp sensor is in the driver side head




what temp should it be at? that's in it's original car and everything. a lot of GM's in the 90's ran at 210*. i think it started with dex-cool but not too sure. where is the temp sensor located, the stock location or...?

[lt1chevelle]

yes the motor still has the steam lines, i have an expantion tank that the line runs into.no the fan dose not have a cowl aroung it.i dont get what you mean by the sides on the rad? no a/c. the rad is not stock its a becool.





Have you cured it,does the engine still have the steam lines,is it a side to side flow rad or up and down,does the fan have a cowl around it,are the sides of the rad blocked so the air is forced through the rad and not around when driving,is the thermostate missing if not have you drilled the 1/8" bleed hole in it,are you running A/C,sorry for the long list but these need to be known, I have a 95LT1,in a 67 camaro,I'm using a side to side alloy rad for a big block,level with puke can , no stat but will fit as this can cause air bubbles in the water raising running temp, also run water as this let engine run cooler by about 20f over coolant. This is what I have found out reading mags on said engine.

[HILROD]

Did you make sure the water pump is the right one for the belt setup you are using? Maybe your pump is the wrong rotation.

[lt1chevelle]

its a electric pump, and yes its working



Did you make sure the water pump is the right one for the belt setup you are using? Maybe your pump is the wrong rotation.

[MrQuick]

How much does your fan cycle during?

I think you might have a combination of problems. The first thing I see is the 160 degree t stat and large tube radiator.

The t-stat needs to close to stop circulation so it gives the coolant in the radiator time to cool down. Thus transfering heat to the fins.

Right now your t-stat opens up at 160 and stays open, the radiator flows so well the coolant is just passing with very little heat transfer. Even if your fan is constantly running.

[paul67]

Just hunted down some info ,the opperating temp for this engine is 220-235 ,low speed fans on 226 off 221 high speed 235 off 231.

[lt1chevelle]

my fan turns on when the car is running. you think i should go with a 190 degreet t-stat?





How much does your fan cycle during?

I think you might have a combination of problems. The first thing I see is the 160 degree t stat and large tube radiator.

The t-stat needs to close to stop circulation so it gives the coolant in the radiator time to cool down. Thus transfering heat to the fins.

Right now your t-stat opens up at 160 and stays open, the radiator flows so well the coolant is just passing with very little heat transfer. Even if your fan is constantly running.

[streetk14]

I have a 160 t-stat in my LS1 with a Griffin radiator and spal fans & it never goes over 180. Temp sender is in the rear of one of the heads. I don't know much about the LT1 motors, but I do have a very good understanding of cooling systems and such.

Am I wrong here, or does the LT1 have that funky reverse cooling system (or was that the LT4) ? It that were the case, I would make sure the pump is flowing the right direction.

Does the radiator have good flow at both idle and when raising the rpm a bit? You should see a good amount of flow from the upper radiator hose with the t-stat open. (edit: you have an electric pump and I'm an idiot :) )

I am assuming that the t-stat is opening and that both radiator hoses are warm when it is at it's operating temperature. Just wanted to check.

If you have a heater, make sure it gets nice and warm. If it doesn't, there could still be air in the system.

When does the engine heat up? Is this just the temp it runs at at all times, or will it creep up to this point at idle and lower speeds? Will the temp come down at all at freeway speeds? I'm just trying to get an idea of whether it is a coolant or air flow problem.

Andy

[lt1chevelle]

i do have a heater but the hoses are not hooked up. the car heats up from start up i drove it for about 10min and it got to 180 but it will keep going. i was driving about 55mph and it was still reaching 220 and look to still be going up but i stoped. i am just real worried i am going to warp a head or blow a head gastket i have way 2 much money in the heads and motor and i cant afford to fix it right now. do u think maybe i have the wires on the pump switch up and its rotating the wrong way? both the lower and upper rad hose are both warm.also let me add the car has no hood on it and its still getting this warm. im going crazy over thing problem:jump:





I have a 160 t-stat in my LS1 with a Griffin radiator and spal fans & it never goes over 180. Temp sender is in the rear of one of the heads. I don't know much about the LT1 motors, but I do have a very good understanding of cooling systems and such.

Am I wrong here, or does the LT1 have that funky reverse cooling system (or was that the LT4) ? It that were the case, I would make sure the pump is flowing the right direction.

Does the radiator have good flow at both idle and when raising the rpm a bit? You should see a good amount of flow from the upper radiator hose with the t-stat open. (edit: you have an electric pump and I'm an idiot :) )

I am assuming that the t-stat is opening and that both radiator hoses are warm when it is at it's operating temperature. Just wanted to check.

If you have a heater, make sure it gets nice and warm. If it doesn't, there could still be air in the system.

When does the engine heat up? Is this just the temp it runs at at all times, or will it creep up to this point at idle and lower speeds? Will the temp come down at all at freeway speeds? I'm just trying to get an idea of whether it is a coolant or air flow problem.

Andy

[paul67]

The engine does have a reverse cooling flow.

[paul67]

Judt thought if the the water pump is not for a LT1 then the water flow is going the wrong way ,but reversing the pump will not cure it as the blades will be wrong for the flow. What is the pumps part number and whats the make.

[lt1chevelle]

its a csr part number:CSI-901LT1

[paul67]

Ive been to there web site and they have a tech number, i would give them a ring as it could be something simple.

[streetk14]

I was thinking the same thing about reversing the pump wires to make it spin backwards, but I think you are correct; The impeller is probably only designed to run in one direction.

If you got a standard rotation electric pump, that could very well be the problem. I'm not really sure what effect having a standard flow pump would have on a motor that has a reverse-flow cooling system, but it cannot be good. Maybe the coolant is trying to climb up the radiator instead of down, causing poor flow and high temps.

Just a thought, but I told you before that I don't know much about LT1 motors in particular.

Andy

[lt1chevelle]

i have the right pump for the car. i had it started yesterday and the upper rad hose gets hotter than the bottom. also tomorrow im going to try and lower the rad. with the lt1 motors you have to run an expantion tank and it has to be higher then the rad. it is higher right now but im going to lower the rad a little bit more anyways. they say if its not high enough you can get air pockets. i really dont think i have any air pockets becuase i can hear the pump pumping the water and see it moving when i take the expantion tank cap off.

[avewhtboy]

take the thermostat out completely and try it and put the thermostat in some water with a thermometer and heat it up to see when it opens. Also what about your fan shroud...some pictures might be helpful

[lt1chevelle]

i dont have a shroud on the car. i think i might order one tomorrow from summit. also if i have my fan on the front of the rad(out side of the engine bay) should it be pulling or pushing air?





take the thermostat out completely and try it and put the thermostat in some water with a thermometer and heat it up to see when it opens. Also what about your fan shroud...some pictures might be helpful

[shep]

If it is outside the engine compartment IE behind the grill but in front of the radiator it should be pushing. That is not the most efficient way for the fan to be mounted. If you have the room move it to the other side of the radiator pulling air.

[lt1chevelle]

things are tight on the other side due to the water pump. i know for a fact that i would not be able to add a shroud if i did move the fan to the other side.

[streetk14]

I don't know the exact numbers, but you lose a lot of cooling efficiency by using a pusher fan (mounted on front of radiator). They will also lose 25% of their flow if a fan that is designed to be a puller is used as a pusher as the blades are usually optimized to spin one direction. You also don't have a shroud you say, which makes the situation worse. I'd like to know what size and model fan you are running. Pics would be nice.

I'd also like to know what the thing runs at @ 65 mph +. That should eliminate the fan from the mix.

Andy

[lt1chevelle]

here you go http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRO%2D67016&N=700+0&autoview=sku

[Charley Lillard]

How many inches from the rad to the water pump ? You need a good fan- shroud combo. What is the timing set at ? Not enough advance will make it run hot.

[paul67]

When you first stat the engine ,keep it ticking over ,and keep placing hand on rad to see if the water is flowing round and not just heat trasfering ,Watch your hands.

[lt1chevelle]

When you first stat the engine ,keep it ticking over ,and keep placing hand on rad to see if the water is flowing round and not just heat trasfering ,Watch your hands.


cant i just turn the pump on? becuase its an eletric pump so turning the motor over would not turn the pump on?

[lt1chevelle]

i dunno what the timing is set at pcmforless did all the tuning so i would have to call them. as for how many in away i would have to look after my class this after noon.




How many inches from the rad to the water pump ? You need a good fan- shroud combo. What is the timing set at ? Not enough advance will make it run hot.

[paul67]

Ok turn motor on then turn pump on , see what happens when putting hand around rad . Do you run engine then turn pump on when engine reaches a certain temp then turn the fan on,

[lt1chevelle]

no i turn the pump on when i start the motor and the fans come on when the car is started.

[paul67]

I'm running the same engine as you i will go and measure my rad back in a bit .

[paul67]

Ok
Alloy rad core dimensions 23" wide,18" high,3" deep.
Tanks LH side 3"x3"x18" RH side 3 1/2" x3"x18"
Fan 16" puller
Lower rad hose which has the thermostate goes to the RH side
Upper rad hose goes to the left hand side.
In front of rad is an A?C consensor ,the rear a trans cooler.
Catch can is the same level as top of rad.
Hope this is of some help.

[lt1chevelle]

ok well i am going to pick and pull (bro blew the rearend in his truck) when i get back ill pull the t-stat and make sure it is working the right way, and try seeing if i can move the fan on the back side and i will get back to you guys. thanks a ton for all the help guys. ill be back later with some info :fingersx:

[Mayhem]

also tomorrow im going to try and lower the rad. with the lt1 motors you have to run an expantion tank and it has to be higher then the rad. it is higher right now but im going to lower the rad a little bit more anyways. they say if its not high enough you can get air pockets.


I agree with what you are saying here.

I have an Impala SS as my daily driver. I will say that even the factory setup has been hard to bleed at times. In My opinion the LT1 is very picky about airbubbles. I had tried to bleed it with the front end higher than the rear in my slightly slpoed driveway to no avail. I also did it Level with no success. When I though that I had gotten all the air out I was wrong. I ended up backing up the driveway so the rear end of the car was higher, and even though it went against my common thinking it bled out a huge air bubble. I don't know why it seems so picky but it is.

I also run Water Wetter by Red Line to help the antifreeze/water keep it cool especially with the heat here in the Sacramento area.


One other thing that I noticed about the factory Impala setup is that the t-stat housing has a bleeder on it. Even though the t-stat housing is lower than the expansion tank and the radiator. I am wondering if you kept the bleeder it when you transplanted it into your Chevelle, or did you use a non-bleeder type to help you line up the rad hoses. Just thinking. Hope it helps

[alittle1]

Here's an article on cooling systems that you should read to help you out with your problem: http://www.crankshaftcoalition.com/wiki/Bulletproof_cooling_system

In my opinion, I think that you should change the thermostat to a 180 or 192. Change the fan to a puller, put a shroud around the fan so it will suck some air through the rad. Adjust the timing properly. Put some higher octane fuel in the engine so that it will run cooler. And lastly, if this is a new engine build, because the engine is seating itself in there will be additional friction and heat buildup, dump the oil and rid the engine of all that pre-lube that will clog the oil pump and screen, make sure that your mechanical temperature gauge sending unit is in the stream of coolant circulating in the engine, make sure your advance is working on your distributor and change the jets on the carb.

[lt1chevelle]

thanks ill take a look at it ill see about moving the fan, if i do move it there will be no room for a shroud. i am running 91 in the car right now, and doing the timing is all done by computers becuase the lt1 motors do not have distributors they have opti spark(pain in the ass) so i would have to take it to a shop to get it done, i dont have the sofware to do it myself. im going to work on the car now be back later, thanks guys



Here's an article on cooling systems that you should read to help you out with your problem: http://www.crankshaftcoalition.com/wiki/Bulletproof_cooling_system

In my opinion, I think that you should change the thermostat to a 180 or 192. Change the fan to a puller, put a shroud around the fan so it will suck some air through the rad. Adjust the timing properly. Put some higher octane fuel in the engine so that it will run cooler. And lastly, if this is a new engine build, because the engine is seating itself in there will be additional friction and heat buildup, dump the oil and rid the engine of all that pre-lube that will clog the oil pump and screen, make sure that your mechanical temperature gauge sending unit is in the stream of coolant circulating in the engine, make sure your advance is working on your distributor and change the jets on the carb.

[lt1chevelle]

ok might have somthing, when i was looking at the car i noticed my upper right(looking at the car) rad hose gets way hotter than the lower left one dose. but the lower left one is the one going to the t stat and the upper right looks to be the return one. dose this sound right i think it is but wanted to throw it out there and see what u guys might think. also my rad is a be cool cross flow.

[streetk14]

ok might have somthing, when i was looking at the car i noticed my upper right(looking at the car) rad hose gets way hotter than the lower left one dose. but the lower left one is the one going to the t stat and the upper right looks to be the return one. dose this sound right i think it is but wanted to throw it out there and see what u guys might think. also my rad is a be cool cross flow.



One radiator hose is always going to warmer than the other. In fact, before the T-stat opens the upper hose is usually operating temp and the lower is still room temperature. Even after the t-stat opens, the lower hose is a good amount cooler as the water has just passed through the radiator cooling it off.

Now, usually the hose that goes to the t-stat from the radiator is the one that should get hot first. I know that's true on the older SBC motors as well as the new BMW stuff I work with every day. Not sure how an LT1 works since it is reverse flow. Maybe somone else with an LT1 can help.

Oh, and I do have to mention that I don't think that fan is enough even with it mounted on the engine side of the radiator. 2000 CFM isn't a ton of airflow and you may need to upgrade. I'm not saying that is the cause of your problem right now, but it will be an issue. I had a 16" Black Magic fan that was rated at 2800 CFM on one of my cars a while back. It could never keep up in warmer weather at low speeds.

Hopefully you get to the bottom of this.

Andy

[lt1chevelle]

thanks man i hope i get this delt with soon im suppose to be going to a car show sat lol again thanks for all the help

[streetk14]

thanks man i hope i get this delt with soon im suppose to be going to a car show sat lol again thanks for all the help


No problem, I know how frustrating something like this can be. I had a problem with my LS1/LS6 motor after I put it back together when I swapped my heads, cam and put on the blower.

I did a lot of things at once, and after I got it running again it would heat up at idle speed only. Bringing up the revs just a few hundred rpm would cool the motor back down. I decided it had to be coolant flow related and the cause ended up being the Bosch water pump I had installed (replacing my OEM pump that was leaking from the weep hole) during the parts swap. It was either a defective part, or a bad impeller design. I guess you get what you pay for. I installed a new OEM pump from the Chevy dealer and problem solved. Thankfully, my diagnosis was correct and I did not throw away a bunch of cash chasing down the problem.

Andy