Last Lemming

I've been having a problem with my car overheating but only at idle, it runs fine when it's on the road. I've replaced belts and pump, thermostat and thermo switch as well. Now I just want to make sure it's bled correctly to eliminate that as a factor.

I have my car on jackstands (front wheels only) and I open the bleed screw and nothing comes out. If this happens do I need to pour water in the fill tank until water starts coming out and shut the bleed screw before it stops coming out so no air is trapped?

In other words if I don't have fluid coming out when I open the bleed screw and I just close it at this point will there be a air in the system, enough air to calls problems. Even if it is just a little air in the tube that runs from the bleed screw connection to the fill tank?

bordin34

If fluid isnt coming out the bleed screw then the system is not properly bled. This is definitely not the smartest way to do it but what I do initially is open the bleed screw, take off the tank cap, and put my thumb over the overflow hose to plug it. I then put my mouth onto the tank and blow until some coolant starts coming out the bleeder. Try not to get any coolant in your mouth it is toxic. Then I bleed with the car running and follow the normal procedure.

william_b_noble

if you don't want to do this with your mouth, just squeeze the top radiator tube

but, something is very much wrong if coolant doesn't come out - maybe you are very low, maybe something else. The coolant tank is above the bleed hole level, so water should flow out. Find out what's wrong.

Dubai944

Use a coolant pressure tester.

jeffrsmith

If you don't have access to a pressure tester, the way I do it is to remove the pressure cap from the the overflow tank, remove the bleeder screw, squeeze the upper rad hose and put your finger over the bleeder hole, release the hose, take finger off bleeder hole - repeat until you get fluid flowing from bleeder hole, replace bleeder, top off overflow tank, replace cap, call it done.

Van

Yeah, if water (coolant) doesn't just start flowing out itself, you have some other problem... like some passageway blockage...

Last Lemming

Does it matter if the fill cap is open or closed when I'm checking to see if fluid is coming out

Also to be clear as soon as I crack the bleeder I should see fluid correct?

The reason I ask is I cracked the bleeder and nothing came out, I then opened the filler cap and some fluid did come out. I also cupped the filler with my hand and blew into the tank a a little bit came.

86 951 Driver

Use a pressure tester as mentioned. Also I would drill a small hole on the thermostat to help with bleeding.

Van

I would not do this - the thermostat acts as a valve for 2 distinct "loops" of coolant flow. When one loop is open, the other loop is closed, and vice versa.

Drilling a hole in the thermostat, or, heaven forbid, removing it completely, will reduce flow through the radiator and reduce cooling performance.

For bleeding the system, if the engine is cold, remove the coolant reservoir cap. Also, there is no harm in giving it "mouth-to-mouth-resuscitation" - just remember to pinch the overflow hose.

If the engine is warm, there should be enough pressure in the system (from the liquid expanding) to push air out on its own.

If you find that you keep bleeding the system, but that it keeps getting air into it, you have a bad head gasket.

Last Lemming

I went back and checked the air in the system the way you all described it and I get fluid when I open the bleed screw. Also there is no loss of coolant and the previous owner changed the head gasket and I of course changed the water pump and radiator. Also when I first filled the system I did use a pressure bleeder and I did get a constant stream of water out the bleed screw but I keep getting a temperature creep at idle.

It looks like the previous owner may have used stop leak in the system Is it possible that has clogged something internally on the engine? Even though it runs at perfectly normal temperature while underway?

Van

I have taken apart engines that had stop-leak in them, and passages ways were definitely reduced!

Last Lemming

Is there anyway to clean out the engine without taking it apart like some kind of detergent? How bad was the reduction was it built-up thick was it a thin cover?

There does seem to be some thin film of material on the inside of the tube that connects the engine to the fill tank.

Do you recall if those engines had overheating problems at idle at all?

LuigiVampa

This ^^^ and listen to whatever Van says!

Van

I'm not sure how to get it out with the engine disassembled!!

This was in a car that sat for many years, so I do not know its history or how it ran at idle.

Have you verified that your radiator fans work?

Last Lemming

Here are me know facts:

The car takes 15-30 min. of driving around to get up to temperature to where the oil pressure drops to its lowest reading of 2 bar at idle.

PO had head milled and rebuilt after head gasket leak - engine has rebuilt head and widefire HG. Invoice shows a flush, but when I drained the system there was all kinds of small particle stuff in it. It's as if the stop leak was put in after the head gasket was fitted. But if there was a head gasket leak into the coolant you would think I would be overheating when I rev the engine, not cooling down. And I'm assuming stop leak was put in at all, but it looks that way at least. He also had rod breading and oil pan gasket done.

I put on new water pump, new thermostat, new thermo switch, new belts, new radiator.

I DID USE A COOLANT PRESSURE TESTER - after it was all put back together. I bled system until constant stream of water came out. While car was jacked up.

I also filled tank and cracked bleeder and fed water into tank until even more water came out bleed screw.

I did notice in the rubber hoses and the in the metal pipes a light brown film attached to the sides of the metal pipe that could be scraped off with a pick. See movie below for what rubber hose looked like.

http://www.youtube.com/watch?v=1wKir...ature=youtu.be

The car runs cool as long as it is moving. Only at a stop does the temp creep. If I blip throttle the temp goes down, and if I turn on heater the temp goes down.

My fans both kick on at low and high speed.

Oh, I do not have a heat shield for my oil filter.

So my questions about bleeding is b/c I think the system is bled well enough. But I keep getting my temp creep at idle. So Im thinking its one of three scenarios:

1. something is clogging the passages causing a hot spot, not sure how likely this is.
2. the thermostat is not opening completely not letting water circulate fast enough.
3. new water pump is bad or belt is loose. I don't think this is the case because the belt only turned 90 degrees after I set it with the Arnworx tool.