s928s

I cannot get my cooling system to bleed.. I have filled the system as full as I can. To the top of the coolant bridge with the fitting on the top. Bleed the radiator to the top using the overflow hose. Still after running it for aprox 10-15 min. the expansion tank fills to the top and there does not seem to be alot of
coolant in the upper radiator hose. The hose does get rigid with pressure but I am not sure about the flow.

I drove the car this am after putting the radiator back in , came to temp withing the first 5 min, stayed dead center of the gague. Then 10 -15 min. into it the drive, is statrted to creep to the upper white mark and then over as I sat at a light. When traffic moved temp would lower.

This is what I have corrected so far:

1. Cylinder head gaskets have less than 300 miles on them since fresh rebuild.
2. All hoses have been replaced under the hood with the exception of the 2 rear that go to the heater core.
3. Radiator was just flushed and checked, replaced right side tank,gasket and rechedked, ok
4. While the rad was out i looped the 2 rad outlets with a hose and pressure tested the balance of the system. Held 17lbs of pressure for 20+ hours.
5. I am expierencing NO coolant loss at this time
6. New cooling temp sensor for gague and radiator fan switch in rad.
7. Waterpump just replace with reman, Cast impeller
8. Thermostat and gasket are new as well as the gasket internal to the coolant bridge.
9. Converted to 2 12" 1550 cpf electric fans tired to coolant temp switch on rad. I also have an overide switch in the car
10. Still have the front condensor fan installed also for higher temps.
11. heater control valve is new and I will trigger when commanded open by the HVAC panel.
12. New radiator overflow cap...Tank is not leaking .

Ant thoughts, Input or tricks on bleeding would help...Please

Dennis Wilson

If the hoses from the top of the radiator and back of the thermostat housing aren't plugged the system should be self bleeding. Have you checked the airflow of the fans to make sure they are pulling instead of pushing? Is your temp gauge accurate?

Dennis

Mike Frye

+1 on the self-bleeding. I've heard that for all of the cars.

Ok, so it crept up when the car was sitting still. You have a set of headers in there, which may be getting things too hot under the hood when you sit still, no?

First thing I'd check is the temps of various parts of the engine with an IR temp gun. First when the gauge is reading in the middle, and later when it starts to creep up. It may be that up to a certain point is OK, because it's actually just a few degrees warmer than normal, over that is an issue and you'll have to deal with it if it gets past that point.

Another option would be to install a temp sender and gauge that will give you an accurate reading of the actual water temp rather than using the inherently inaccurate stock gauge.

Since it comes back down when you start moving, it must be circulating and the pump must be doing its job, same for the fan and radiator, as well as t-stat.

I think you may be relying on a stock gauge to do something in a non-stock situation. Your car is modified so much that you may need to figure out what is 'normal' and then work with that.

Dennis Wilson

Other factors that can affect engine temps are ignition timing (if too advanced) and a lean A/F mixture. May want to investigate those.

Dennis

hacker-pschorr

I ran into a very similar problem a few years ago. The thermostat was installed backwards.

s928s

If the hoses from the top of the radiator and back of the thermostat housing aren't plugged the system should be self bleeding. Have you checked the airflow of the fans to make sure they are pulling instead of pushing? Is your temp gauge accurate?

I will have to check the flow through the heater core. The fans on the engine side of the rad. are Puller fans. I am also using the condensor fan as a
pusher fan.

You have a set of headers in there, which may be getting things too hot under the hood when you sit still, no?

Headers have been on for years prior to rebuild. Since rebuild they have been ceramic coated prior to reinstall.

Other factors that can affect engine temps are ignition timing (if too advanced) and a lean A/F mixture. May want to investigate those.

I will double check the mixture the timing I know is dead on, I just put another belt on last night. ( that is another story)

I ran into a very similar problem a few years ago. The thermostat was installed backwards.

I am confident the t-stat is installed. Base is facing the motor against the inner housing seal. Top, domed part, is facing the radiator with the small bleed valve the top.

Thanks for all of the input, DAVID
.

928worldwide

David this happens to me frequently after timing belt WP jobs. Squeeze the upper and lower hoses to move the coolant around, keep the vent in the top of the RAD open until you see flow, and keep opening the coolant res and topping off until you see flow out of the RAD vent. You might have to shut down, start up, shut down, start up a few times during all this, that usually does the trick for me. Also, make sure the heater is on full blast.

s928s

mason..I though you just take things apart !!! I did not know you knew how to put them back together



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123quattro

I have headers on my car and they have caused zero cooling issues. My car is dead nuts reliable cooling wise. The system does self bleed as well. I just fill the reservoir and it works just fine. I've have had to do this 3x so far and have never had air pocket issues. Something is up. I would look towards the thermostat. Maybe pull it and do a test on the stove with it? Either that, or you need a new radiator.

dr bob

Heats at stop, cools when moving... Sounds like the fans aren't running.

s928s

Fans are running, I have them switched on as a constant at this time. The condensor fan also comes on when at temp.

Mrmerlin

from your report, I would replace the thermostat and verify the thermostat rear seal is in fact in good condition.
Also use the lower temp thermostat 75C.
I would replace the oil cooler thermostat and the 2 springs, ( this part fit into the opening just on the other side of the sender)

And to bleed the system run the car with cap off till the fans come on and with the heater control full open, once this is done, refit the cap then drive the car for about 5 miles.
Park it and let things cool off once things are cool top up the bottle as necessary, leave the cap on till its cool

928worldwide

It's air in the system, I bet. Everything is Tidy in there knowing David. This is just an air bubble IMO. Let us know Dave.

s928s

the thermostat and the gasket/seal internal to the coolant bridge and both factory parts and are new. I have good oil pressure and a remote 14 row remote oil cooler with 5/8 line in and out.

Tried to bleed it again here at my lunch hour.
1. topped off the rad. by pulling vacuume through the top vent line, this draws coolant in from resivoir and block.
2. topped off the block by filling to the top of the bleed fitting on the coolant bridge
3. zip tied the heater valve in the full open position

..ran engine with the cap off, came to temp as normal noticed the following
1. temp went to normal range , noticed the upper rad. hose was getting hot ( hose from top of rad to the block inlet.
2. started to get heat through the heater inside
3. temp rose to upper white line. both hoses felt hot. lower hose was cooler than the upper.

still appeared to have an air or flow issue.
1. when running at the higher temp I disconnected the upper line on the radiator and no coolant came out? ( normal ??)
2. once it cooled some you can still feel "air" in the upper rad hose like it is not full.
3. coolant level in the expansion tank seems to rise every time. I seems that air is almost getting into the system. I fill the rad. and the block to the top. after running the engine it seems to
loose some of the volumn of coolant. No leaks on the ground..possibly pushing it inot the resivoir.

mark kibort

see if the entire radiator is smokin hot when its over heating. sounds like it isnt as the lower radiator hose is cooler from what you are saying . this is a radiator clogged problem, or t-stat issue (air in system) . easy way to fix the t-stat issue is to wedge it open. very easy to do. (2) 10mm bolts come off the housing, pull out the t-stat. take a small toy brass gear (or somethinge else that wedge the t-stat open) and pull open the t-stat and slip the gear over the front shaft repalce into socket. now, it is wedge open.

bleading is a matter of ONLY , squeezing the upper and lower hoses when the system is cool to burp out to the reservoir, any air in the system. this is ALL you need to do.