Ked928

Hi Guys,
I need some advice on an issue.

Ive have 928 1985 4.7 Euro , and it was having a little overheat issue when i was in heavy traffic it went up above the second line and red light come on. But when i got going again i guess the air cooled it back down, and driving around other days i would never go up. So found the fan wasnt spinning at idle so i got that replaced.

Now its spinning good at idle, but now 1 day later it goes above the second line and red light comes on everytime and stays there , even when im driving in the clear , doesnt come down below second line. Drove for 1 hour to get home and above all the way (worried the whole way) (no steam though)

Someone got a heat gun out and it read 80 degrees Celcius on the thick tube going into the radiator and 50 degrees going out of the radiator. (at this point above second line and red light on)

So he said thats about right , the radiator is doing its job , must be sensor.
So i guess my question is , does this seem right, is it the sensor ?
I put 4 litres coolant in (so perhaps water level bit low but his done nothing) 5 mins later someone driving beside me says im leaking coolant, so it spat the coolant out, maybe i over filled it ?)

Do those heat levels look correct?
Is there any other test i can do?
I just come drive don't want it to blow.

Any help would be appreciated.

StratfordShark

I'm confused about volume of coolant in system. You say you added 4 litres - did you mean 14? It's not going to overflow from anywhere, so I would check level in expansion tank when cold, then look for any leaks.

Leaks hard to see on hot engine as fluid evaporates fast, so a kit to pressurise at expansion tank when cold is handy.

Cheap and simple fixes are new t-stat, new sealing ring behind t-stat, new pressure cap.

Mrmerlin

most probable leaking areas,
the heater control valve and short hose ,,
the right top of the radiator where the hot coolant enters,
and the water pump weep hole ,
and the hoses that attach to the water bridge or the radiator.
Best to replace the HCV and short hose the thermostat and the rear seal and O ring and coolant bottle cap

\ NOTE the coolant system holds about 16 sixteen liters of coolant,
8 coolant and 8 distilled water,
adding 4 liters is about a gallon

docmirror

Lot of parts on the 928 cooling system. Diagnosis is the key. From what you've said so far, you have; a) coolant leak. b) sensor concern. c) new fan clutch. None of which has cured things.

I would run tests and see where you stand. First, get one of those hand pump pressure testers for cooling systems. Since you are in Yerrup, I have no idea what you have for tools but it looks like this:


One of those adapters will fit snug on your overflow tank, and then attach to the pump and gauge. Hand pump it up to 6PSI, and start looking around the rad, hoses, heater hoses, heater valve on the firewall under air filter cover, heater core inside. Also watch the gauge on the tester, it should hold at 6PSI for a long time. If it's going down slowly, you have a leak somewhere. Find it.

Next, remove the spark plugs. Look for one that is very white, almost new looking. If you find one, you have a failure in the cooling jacket of the engine, or more likely in the head gasket. Hope you don't find this. Put the plugs back in.

Next, take off the center front cover, and expose the belt path and water pump. Look for metal debris around the shaft of the pump pulley, or look for the pulley to be tilted on a funny angle, indicating a bearing cartridge failure. If this looks good, use a bright flashlight and locate the weep hole under the pulley, see if you find coolant drooling out. Any issues in the whole area indicate need for a new water pump.

Lastly, it could be that the impeller in the water pump has come loose from the shaft. That can only be inspected by water pump removal. this is a good time to plan a water pump and belt renewal. Report back the findings of the above tests.

Mongo

Where is the coolant being spit out of? Is it the overflow tube on the reservoir? If there is no other leakage (like from a faulty heater valve under the airbox), definitely do a plug check. If you have an inspection camera, you can probably shove it down the spark plug holes to look at the cylinders. Any presence of coolant will tell you that you have an internally failing head gasket, likely at the water jacket toward the rear of the heads. I have heard of this failure many a times with 2-valve heads and even with my 944.

Ked928

Coolant is coming out the overflow because its overheating. I put some more coolant in , ran the ran for 10 mins and it overheated again when the collant level was full.


could it be the thermostat or the water pump ?

V2Rocket

where on the gauge ?

Tony

see this thread.

https://rennlist.com/forums/928-foru...es-93-gts.html

granprixweiss928

how old is our water pump and your radiator?

BrianG

If you overfill the reservoir then coolant will overflow because of expansion difference when the engine is hot. Are you filling past the cold-fill line on the reservoir?

docmirror

Did you even see post 4? Oh well, cya.

M. Requin

never mind

Ked928

sorry ive been out, i really appreciate all the responses.

StratfordShark - i put 4 litres (there was nothing in the reservoir so i filled it up to the line which is halfway in reservoir) but then when hot it splits it out again
Doc i got hold of a pressure tester , doesnt seem like there are any coolant leaks , nothing i can see . spark plugs are fine, There doesnt seem to be any debris , so perhaps it is waterpump as you say.
Mongo - coming form overflow tube
V2 rocket - its a different gauge on the 85 Euro , But there are 2 lines , and its above the second line and when its above the second line the coolant light also comes on
BrianG - so if i just put in 4 litres when cold , it will just spit it back out when hot ? so how do i get it in and keep it there?

Basically it just overheats in 5 mins and spits the coolant back out of the overflow. The i can hear it boiling down underneath.
Could this just be T-stat cauing this? I hope so
But looking like water pump replacement , what is an OK price to pay someone to replace waterpump and timing belt ? estimately

Mrmerlin

from the info your water pump impeller has failed,
dont keep testing the engine you may damage the headgaskets.
Replace the water pump.

post a location so to steer you in the right direction

928NOOBIE

PSA BUMP: I love to drive and I do it even if it's just running around a route I have within town...

Summer ..drive lots.

Hose the bugs and junk out of those radiators...do it like it owes you money.

Get a new radiator cap ....and that's triple if you can't remember the last time you did...

Floor it with something awesome playing on the radio. Do it again.

Peace.