LT1 Overheating!!!

What a challenge i am having a real tough time keeping this motor cool. I can run it for about 15-20 minutes and then i get a ton of blow back from the expansion. I felt like i had the air out maybe not. Anything i should definitely do before i dig in to things further?

Is this happening when driving or just sitting idle? Is the radiator new or old, maybe blocked? How do you have your steam vent lines run? I am not familiar with LT motors but that may help someone else with your issue. Probably like you said, air in the system somewhere.

I'm going to check the steam lines tonight. Everything is new on this except the Lt1.
I only notice it happens under a rpm load. I don't believe it has happend under normal idling conditions.

pull the top of your water pump off (should be two small bolts) when the engine is cool, add coolant directly to the engine block...i had issues for a while with my car, turns out I was getting air bubbles into the water pump, this is a great time to replace your thermostat if you don't know how old it is, for diagnostics purposes you can actually remove the thermostat. When you get air bubbles in the water pump the coolant stops moving and can sit in the heads and boil. You should also have a bleeder on the top water pump hard pipe: once you've filled the block, reinstall the parts you've removed, open the expansion tank cap and remove it, then start the car and run it, topping off the expansion tank occasionally while watching for air bubbles...you can also rev the car occasionally to pull coolant into the engine. Keep a close eye on your temperature and let us know if any of this has helped!

Good luck bud!
Ethan

Has the expansion tank cap been replaced? If not, replace. If it is new check its function and the sealing surfaces.
When bleeding/heat-cycling this system, be it V8 or L4, the front DS must be as high up as possible. I pull up onto one ramp facing up my driveway. Run and allow the fans to cycle while revving and holding the engine at ~2000rpm. Let the system cool and repeat.

Also would like to know how you routed the steam vent line.

I would replace your T-stat too; test the function of the replacement in a pan of boiling water.

The steam lines T's into the expansion tank. I think that is correct. The expansion tank is the original. I did get a 16psi cap for it so that is right. I did add fluid directly to the pump a few weeks ago but i will try that again because right now im at a loss. It has to be an air bubble somewhere. Thanks and i will let you know what happens.

Ok failed again. Ran the engine at idle for appox. 1 hour. i would crack the bleeder valve and felt good about all the bubbly fluid coming out of it. It would kind of spurt and burble and then the stream got longer and more frequent (no this isnt a enlarged prostate commercial). at almost the hour mark of screwing with this the expansion tank filled and popped the 16psi rad cap then when i would open the bleeder valve just steam was coming out.  WTF!! I had the car sitting on an incline as well to help with air.This is my steam line routed into my expansion tank,Is this wrong? [You must be registered and logged in to see this image.]

It may not make a difference but I have my steam lines switched. the motor line was a straight shot and the radiator side is at the 90 deg. Have you tried bleeding it with the radiator cap off? Clarks garage has a protocol for bleeding the air out of the system, it may help.

Arthropraxis wrote:It may not make a difference but I have my steam lines switched. the motor line was a straight shot and the radiator side is at the 90 deg. Have you tried bleeding it with the radiator cap off? Clarks garage has a protocol for bleeding the air out of the system, it may help.

yeah thats how i started off but the fluid ended up backing up in the expansion tank after time.I ordered a inline steam vent from jags that run so maybe running the steam into the rad will help make a difference Im at a lose i hope this works.

Take the line that you T'd into off the tank ans run it directly from the motor to the radiator. Do not run it to the tank. Plug the line coming from the tank.....
You are getting air in the system from the top of the tank when it heats up and the sucking back in as it cools down. Try it, bleed the system completely and you should not have the over heating issue.

WOW awesome, I thought that may have been the issue but was not sure. I had someone else run my coolant lines and for some reason they must of thought that was correct. Alright im feeling real good about this again. I thought the steam vent routing was wrong but was unsure.

Ok one more question and I will call this thread history. Do we still follow the full line on the expansion tank or do we put more in?

In my opinion if you can see the fluid level in the reservoir its enough to where it should not be overheating. I would run it at the full mark on the tank.

Alright just ran the car for about 45 minutes. It ran great! When i got in the drive way though i noticed the expansion tank had popped off after it sat for a minute, on further inspection i noticed the tank is starting to swell. The gauge in the car is reading around the halfway mark which is better than before. I tested the thermostat and it works fine. Like i said before the rad cap is 16psi so i believe that is correct. Im at a loss i really though this issue was over and i could start on the next. Any ideas what it could be? The fluid is like bubbling up in the expansion tank.

Can you take pictures of how you have your coolant lines hooked up? I never had any problems with mine...

Here are the pics of my coolant routing.[You must be registered and logged in to see this image.]

Ive got my lines run similar to yours. Only difference is that Ive tee'd my steam vent into the back corner of the reservoir from that line your holding in your hand in the 4th picture.

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You can kinda see what I did in this pciture

I deleted that i think Admin was telling me that needed to go. Has anyone had there coolant back up in the expansion tank? Mine is doing that and seeming to be extremely hot. At this point i would drop a deuce on the car if i thought that would help.  I have bled this thing quite a few times, boiled the thermostat to see if it was junk(it was fine) it seem to be running fine a few days ago and like i said a few post ago ran fine while driving and when i got home 2-3 minutes the rad cap popped and coolant spewing everywhere. I need a little help with this one. Today i pulled the ac condenser just incase it was slowing the airflow, No dice. Opened the bleeder valve while running just steam coming out. Im at a extreme loss.

The hose that comes from the reservoir should only go to the pass side of the radiator and the steam vent from the rear of the heads should go to the small nipple on the reservoir. If I understand how you currently have it plumbed the steam vent is technically dead headed.

948 wrote:The hose that comes from the reservoir should only go to the pass side of the radiator and the steam vent from the rear of the heads should go to the small nipple on the reservoir. If I understand how you currently have it plumbed the steam vent is technically dead headed.

Ya, thats how I've got my 3/4" line run from the tank. Sorry, thats the other thing I did different to yours and I never had any problems. I used tee's from jagsthatrun.com to tee into my rad lines and I've got a universal summit rad with ford contour fans that run from the ecu if that helps you any...

Here's how I have my coolant hoses run, has worked great! One thing you need to watch out for is making sure there are no kinks in the steam vent line from the back of the heads, that the hose is clamped tightly, and that it has a general up-slope to the expansion tank...if it jumps up and then goes back down to the expansion tank you can get air trapped in the system.

Also, try filling the cooling system from the water pump, it will help purge caught bubbles in the engine block, you can also try running without the thermostat for while to get the system moving with less restriction. When I purge air out of my cooling system, I run the car with the front up a bit (either on a hill or jacked up a little) with the expansion tank OPEN, running the heater on full, cracking the bleeder in the upper water pump pipe frequently to purge air and steam out of the system.

Back of the motor, you can see my steam line down there.
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Drivers side, steam line running to the expansion tank
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Radiator vent pipe capped
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Passenger side
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Drivers side
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Good Luck buddy!!!

Also, the small nipple from the DS of the rad should go to the small nipple on the rear of the reservoir.

So the small nipple that runs from my hot fluid return and the steam vent both tie into the expansion nipple?

kelleysj wrote:So the small nipple that runs from my hot fluid return and the steam vent both tie into the expansion nipple?

I assume that the "Hot fluid return" is the tee on your upper rad hose? If so, then yes that and the steam vent coming from the rear of the heads should run to the rear nipple on the reservoir. Obviously the tee output in your upper hose should face directly up and be as high as possible to help remove air from the radiator

Ok I think i got it! I broke the darn plastic barb on the expansion tank so i had to find a fitting that i had to make work will see if it works but so far so good let it idle for a while and took it for a 15 minute drive.[You must be registered and logged in to see this image.]