still overheating

[basher79]

When she overheats shes loses of lots water from expansion tank, also noticed that hoses are pressurized and radiator still cold at bottom, thermostat definitely works as i tested it before i put it in.
we had this same problem on a gti golf and it was the water pump

 

[n18rks]

all are hot apart from the bottom one that connects to radiator - previously suspected faulty thermostat, got new one and tested it in saucepan on stove before fitting - thermostat opened before water boiled - assumed all ok.

 

[n18rks]

is there a way to test the water pump in operation ?

 

[basher79]

not sure if there is a way to test it, if it was mine id take it off to see its not faulty. if thats ok try it without a thermostate. all the symptoms sound like the waters not circulating to me

 

[n18rks]

i will have the pump off and see if i can see anything obvious and dont think i can run it without a thermostat as its contained in a sealed unit

 

[basher79]

yeah have a good look at impeller let us know how you get on, im only up the road from you so if you need any help let me know

 

[digbymole]

sure you can run without thermostat as the engine will just curculate the same but wont have to wait for it to open ,will take longer for the engine to warm up i would try that first then flush the engine through

 

[rodntod]

is there a way to test the water pump in operation ?

Let it cool,remove cap and fill reservoir.Take top hose off rad and while holding get someone to start engine,Should be evident if pump is working as you will get a bit wet.

 

[Datatek]

If you take the pump out, check that the impeller cannot turn on the shaft.

 

[Saint.V8]

sure you can run without thermostat as the engine will just curculate the same but wont have to wait for it to open ,will take longer for the engine to warm up i would try that first then flush the engine through

The V8 Stat is fixed in a small plastic hosing plumbed into the coolant pipe work - can't run without it as it actually fors part of the pipe work system....unlike a lot of cars that are in a housing bolted to the engine!!

 

[n18rks]

Results of this mornings tests

• Filled radiator from top hose, filled system and bled completely of air.
• started and allowed her to warm up
• internal heater chucking out hot air (very hot) with fan on full (air con off)
• allowed to trick over for 55 mins - all ok
• revved to 2500 rpm and kept their for approx 5min - done this on a couple of occasions during the aforemention 55mins - all ok
• water level stayed same throughout test dropping only 1 cm during who time - not due to leak - most likely due to removal of a small amount of air.
• top of rad hot - bottom of rad cold
• top of thermostat hot - bottom of thermostat cold
• heater matrix flow and return hot
• top hose pressurised but still could be squeezed a bit by hand
• expansion hose from thermostat to expansion tank hot and could be squeezed
• radiator bleed pipe hot, not blocked
• no unusual noise ie tapping/knoocking from slipped liner etc
• temperature needle stayed dead in middle and did not move
• visious van speed increases with engine revs
• throttle housing flow and return hot
• no leaks anywhere
• not overheating at all

Took her on a gentle run around the local streets - managed to go for approx 3 miles then bugger me she overheated - this is what i found:

radiator cap releasing pressure
bottom of radiator cold
bottom of thermostat cold
top of rad hot hot
pressure less in pipes less than what it was

my thoughts: water pump is working as the heater matrix would not be able to supply warm air for that amount of time if nothing was being pumped around. This leads me to believe that thermostat not opening when it should be and when driven the heater matrix cooling the coolant is not enough on it own to keep engine cool and needle in middle of temp gauge.Only problem is - this is the 2nd thermostat, this one i tested in a saucepan to check that it works ok which it did.

Don't believe it is a gasket or liner problem as why would it warm up and maintain temperature.

Now thinking of trying to wedge the thermostat open all the time to see if it makes a difference - anyone got any thoughts on this or any other suggestions.

question - when your P38 is warmed up is there much of a difference between the top and bottom in temperature?

thoughts ideas welcome.

 

[Datatek]

I would not wedge the thermostat, I'd mangle the old one fully open. Mines a diesel but the RAD gets hot all over.

 

[Grit Valve]

I wonder if the timing is contributing to the heat ?

 

[basher79]

I would not wedge the thermostat, I'd mangle the old one fully open. Mines a diesel but the RAD gets hot all over
i agree with datetek try that

 

[n18rks]

Fitted airtex water pump (OEM) today - tested it by removing inl;et to heater matrix and it spat out water confirming pump id good.

Filled up and removed air - took on test drive got approx 5 miles and over heated - felt bottom of radiator ...... bloody cold - thermostat cannot be opening - this is the 2nd thermostat i've fitted - this one from Island 4x4 - tomorrow i am going to fit old thermostat that i have "mangled" so that it is constantly open.

Could the cold water on the bottom side of the thermostat stop the thermostat from opening ?

As per previous comments in this thread - not losing any coolant anywhere - all parts in system have been replaced - with radiator being cold at bottom assuming that thermostat is not opening ( despite testing it in saucepan before fitting it ) - cant see that it can be liner or cracked block problem


anyone else care to take a stab at it ?

answers, suggestions, comments and donations welcome

 

[Datatek]

Fitted airtex water pump (OEM) today - tested it by removing inl;et to heater matrix and it spat out water confirming pump id good.

Filled up and removed air - took on test drive got approx 5 miles and over heated - felt bottom of radiator ...... bloody cold - thermostat cannot be opening - this is the 2nd thermostat i've fitted - this one from Island 4x4 - tomorrow i am going to fit old thermostat that i have "mangled" so that it is constantly open.

Could the cold water on the bottom side of the thermostat stop the thermostat from opening ?

As per previous comments in this thread - not losing any coolant anywhere - all parts in system have been replaced - with radiator being cold at bottom assuming that thermostat is not opening ( despite testing it in saucepan before fitting it ) - cant see that it can be liner or cracked block problem


anyone else care to take a stab at it ?

answers, suggestions, comments and donations welcome

The viscous might increase in speed with engine revs but that does not mean it is going at full speed, however RAD cold at the bottom means no circulation so stat is most likely or airlock.

 

[Grit Valve]

I can only suggest no thermo to guarantee wAter flow rad is unlikely as new but you never know if hose Is still getting pressurised I can only assume hgf sorry I have known people or gaskets fail through error ..petrol sorry sealed thermo do yes put your so called mangled stuck open you mean one back Also can you leave it idling this can take at least 15 minutes ( only) tomorrow and see if it over heats if it doesnt overheat ask datatek how to permently have electric fans on and take it out if it still overheats its looking like head !!!

 

[n18rks]

The viscous might increase in speed with engine revs but that does not mean it is going at full speed, however RAD cold at the bottom means no circulation so stat is most likely or airlock.

viscous fan is new, would suck a bag through the grill if i would let it.

Agree - circulation prob i think due to thermostat - is there anyway it could he HG or block prob ?

 

[n18rks]

I can only suggest no thermo to guarantee wAter flow rad is unlikely as new but you never know if hose Is still getting pressurised I can only assume hgf sorry I have known people or gaskets fail through error ..petrol sorry sealed thermo do yes put your so called mangled stuck open you mean one back Also can you leave it idling( only) tomorrow and see if it over heats if it doesnt overheat ask datatek how to permently have electric fans on and take it out if it still overheats its looking like head !!!

Will fit open thermostat tomorrow - if it does not overheat then its a 2nd faulty thermostat and will obtain a 3rd.

If it still ?

 

[Grit Valve]

Will fit open thermostat tomorrow - if it does not overheat then its a 2nd faulty thermostat and will obtain a 3rd.

If it still ?

still got old rad?? If it does overheat with it stuck open looking bad I'm afraid to say