Micha1

Well what do you know....still having overheating issues.

For those who choose to respond, I am not a good mechanic....(not a mechanic at all, so I do ask stupid questions). I live in Canada, so my car is soon going into storage to escape winter.

I have owned my 928S4 for a couple of years. Have with the help of a mechanic replaced bearings in my torque converter very successfully, but do have an overheating issue even in cool weather. I will describe my experiences with this:

1. Needle on gauge always is near last white mark, lately has been going past, red light will come on. Digital readout will say engine is too hot.
2. Other day steam and antifreeze blew out from cap on overflow tank. Did buy a new cap.
3. Sometimes white smoke will come out intake tubes after shutting car off after overheating.
4.Even after engine is hot, the face of the radiator is cool to the touch. Top lip of radiator will feel hot.
5. Fans never seem to run after car is shut off, so I leave the hood up to cool it off. Fans do not seem to come on at any regular intervals. If I do join two wires off of intake sensor, fans will run.
6. I did put in new thermostat and rear seal in the car. Seems to be working, top hose is usually a bit cooler. I usually only get temperatures on the water bridge of about 160F top hose, 158F lower hose. The little hose hooked to the nipple at top of radiator has heat in it.

What I would like to know is:

1. Is there a way to tell if my water pump is good? The coolant level in overflow tank will move when engine is revved. Will there always be turbulence in the overflow tank if water pump is working?
2. Does it sound like my radiator is shot if it is so cool to the touch after car is hot?
3. What is white smoke coming out of intake tubes? No white smoke out of exhaust pipe or smell off coolant in the cab.
4. After putting on new cap, and car getting hot today, a fair bit of coolant seemed to run out from what I think is bottom of radiator. Did not see exactly where, but did have to top up.

Sorry for the huge write up but wanted to give as much info as possible to allow much wiser 928 owners to help. Thanks for any advice

andy-gts

hmmmmm. could the thermostat be in backwards....since engine is hot and radiator is cool , no flow to radiator...

Lizard928

Where in Canada are you?

Micha1

I live in Winnipeg

928 at last

If you've managed to overheat anything in Winnipeg, you most definitely have a problem.

Humour aside, sounds like one of your problems is the radiator. could be a side tank, but you'll have to trace it to find the leak. Easy way is to use a pressure tester (Carefully...not to overpressure the system and cause more problems). You can source these at a local parts store that has loaners or from a vendor like Princess Auto.

Once you have pressure in the system, check the front of the engine carefully to make sure that's not the source of the leak, then go over the radiator to determine where the coolant is coming from.

If it's the rad, parts are available for the end tanks, and if you're not up to doing the job on your own, you'll need to find a local shop familiar with European aluminium rad repair.

If it's the rad, the shop can test it for flow, and if clogged, they may be able to rod it or chemically restore flow to save you the cost of going new or aftermarket.

That's where I'd start, and go from there. there could be a problem with the fan control systems too.

928 at last

Not to be an optimist, but it could be as simple as a hose clamp gone bad, or a hose dying from old age. Be sure to visually check these carefully.

928 at last

Next up. The pessimistic. Check your oil and make sure it still looks like oil and not chocolate milk, (and that there's no oily residue in the radiator). If so, the white "smoke" may be coolant vapour coming back through the intake system.

rnixon

Sorry to be pessimistic too, but it sounds like one or both of the head gaskets have gone.

Micha1

Hi Rob,

Thanks for your input. I am definately hoping for the optimistic side of it. I think it is the radiator as well. The oil is clean as a whistle, not like chocolate milk at all.

If it is the radiator, I have not problem going with the $595.00 aftermarket option from 928Motorsports (I think it is them).

Appreciate your input.

bureau13

928International, I think, had the new radiator...

Lizard928

I think you have numerous problems.

A new radiator from 928intl.com is a good idea, but I'm not so sure it will solve all your problems.

The white steam coming from the intake tubes is very strange, as there is nothing in that area to allow that.

It is likely especially if your car is from japan that your headgaskets are going to have to be done.
When was the waterpump last done? Do you know what was installed?
If you have no record, replace it with a new Laso pump from Roger.

Micha1

Hi Lizard,

Don't know when the water pump was last done. PO had no records. I will use one of those Laso pump when I do replace. How do I know if my car is from Japan? Is there a way to tell if the water pump is working without taking the car apart? I did check under the oil filler cap if there is any condensation and there is not. There is no condensation inside the intake tubes. At least these two findings do not lead to coolant getting into the engine. Thanks for the help

rnixon

If you have no record of the TB & WP having been done, I would do that this winter, regardless of the state of the current water pump. You could well have multiple issues, so I would take the radiator, thermostat, TB, WP, intake and heads (!) off and replace / repair as required.

Running the car very hot can warp the heads. The usual advice is to stop and allow it to cool as soon as you see it getting too hot.

Mrmerlin

lets work on the easy things first.......

I would venture a guess that your heater control valve and short hose need to be replaced,
if they are leaking then you will see smoke from the intake.

NOTE these parts are under the air filter housing on the right side of the engine.


So A new cap is good.
a fresh thermostat and rear seal and O ring are good.

Inspect the coolant tank for color if its tan or brown then its probably time for a new tank.

Inspect the radiator at the top of the inlet hose next to the tabs that crimp it to the core this is where it will leak if the tank is cracked.

Inspect the hoses where they connect to the water bridge these outlets have little tabs on them that can indent the inside of the hose and cause leaks.

Make sure both fans run check the connectors at each fan

Micha1

Hi Mr Merlin,

Glad you chimed in, have read many of your posts. Appreciate thought of working on easy things first. Easy sometimes translates to less expensive.

Have read in regard to the heather control valve and short hose that may require replacing. Happy that this may cause smoke from intake. Never has been a lot of smoke, just a bit. It was a cold day hear today so needed the defrost on. I did notice today that the heater does not blow heat all the time anymore. Today would mostly blow cold and occasionally hot even when I had the dash setting at 85. Never has done this before...hot was always hot. Does that sound like that is indicative of the heater control valve potentially being faulty? Do you happen to know the part numbers for these? I did buy my torque tube and converter parts from Roger, so can go through him again.

Both fans will run, I can confirm this by connecting wires on the intake sensor.

In regard to the coolant tank. Mine does seem to be tan. Are they normally snow white?

Thanks for the help.