Thread: overheating, which way does the water cycle?

OK, been at this now for 14hrs solid and I think thats it for tonight.

Previous owners Attempts:

New thermostat,
New Water pump,
Got the water system fume tested



Things I have done:

Radiator Rodded,
Engine flushed,
Thermostat removed,
Additional earth from negative to engine(havnt tried to body yet)
checked for kinks etc
not sure about this but thought i'd give it a try, filled system with fresh water and removed usual airlocks, when cold I placed a balloon over filler port, waited a minute and the balloon started to fill up, after about 5 mins the balloon was at about 50% capacity with vehicle at idle speed, I had a sniff of the air in the balloon to see if I could smell exhaust(or any contaminant) and nothing, smelt like clean balloon, my mate agreed on this.

basically what is still happening is this: after fresh fill of water and usual airlocks removed we take it for a drive, everything seems fine for about 10mins, the temp sits a little under half way, then all of a sudden, out of the blue it will start climbing rappidly, once it hits what I assume is the danger zone(last white line before the red) we stop and check the hoses and we can grab them without problem(with thermostat in the top one is a bit hotter) if I open the filler cap at this point just a little to relieve pressure we get mainly water spilling out which is only warm but there is quite alot of pressure.

I am worried it may be the head but it is starting to look that way

pump impeller may be shagged, and as its a diesel unless you use a temperature sensitive coolant the usual sniff check that works on a petrol engine wont work.

see if you can extend the radiator hoses from the engine into a large bucket and run it up without a thermostat fitted to see what the flow rate from the pump is...

is the thermostat shagged (Ive had new ones that wouldnt open before)

is the thermostat in the right way round?

Im banking on delaminated head gasket - gasses through the composite gasket at pot 2 or 3 to the water jacket.

If it blows a ballon up at idle when cold I wouldnt imagine you wouldnt smell too much other than air... at idle the engine is pumping mostly air. Bugger all fuel being burnt to smell combustion products.

The only thing I dont get is you say thermostat removed, driving around temps start to climb after only 10 minutes... seems quick in my experience of limping head gasketted 300tdi s. With the thermostat removed 10 minutes is pretty quick - unless you are pegging it up hill.

Can you directly measure the actual water temperature in the head - factory gauge is not reliable.

The water in the resevoir really only has a direct connection to the main flow from the bottom hose, if there is a water restriction in the block or pumping problem the water in the head (where the factory sensor is) could be boiling but not circulating enough to increase the temp in the resevoir.

I like Davids idea of running the bottom hose and top hose from a big bucket just to check on circulation.

Steve

ok, up and had my coffee and time to get back into it, first of all I will be pulling out the water pump for a visual inspection, failing that I will give Dave's water test a go and then thirdly a compression test..

honestly I would be happy to know it was a head gaskit but unhappy to go ahead and just do it if it diddnt fix the problem, it wouldnt be the first time as I have owned many ford falcons.

I was wondering if anyone knows the correct procedure for doing a compression test on the 300tdi, I think it will tell me the truth.

Thanks a heap for all your suggestions, I will post my results.

Cheers.

get a diesel compression test unit. the gauge should be calibrated with a small large scale step from 0 to about 100psi and then cover out to about 600psi in small scale large steps Dont use any gauge that cant handle at least 400 psi

with the engine cold

remove all the glow plugs, remove the fuse or the relay that drives the glowplugs
remove the wire from the fuel pump solenoid
attach the diesel compression test unit to glow plug hole 1
crank the engine for 3-5 compression strokes.
not pressure
repeat for pots 2,3+4
put the glow plugs back
put the wire back (dont forget that bit)

10% variance from lowest pot to highest is the limit of acceptability. and IMHO more than 5% is questionable.

repeat with a hot engine, as a general rule, if the variance is more than 5% on a hot engine then its time to start pondering about contemplating new rings. If it gets worse then its time for headwork in one form or another and a leak down test is in order to work out what


as a precautionary step for doing a leak down test its worth while sourcing or making a leak down adaption for the glow plug to make one just gut an old glow plug and weld an air fitting onto the top If you get more than 10% varience on a hot engine conduct a basic leak down test.

plug the adaptor onto the pot with the lowest compression set that piston to post TDC on the power stroke and lock it in gear, or lock the crank by means of the crank timing pin or a socket and breaker bar on the main pully, remove the dipstick and block the crank case ventilation tube with a finger from a rubber glove.

when you put the air on listen for the escaping air.

out the inlet its the inlet valve
out the exhuast its the exhuast valve
out of an adjacent piston its a delaminating head gasket that hasnt compromised the cooling system yet
out the cooling system its the head or the gasket
out the dipstike tube its the rings.

Drop the pressure off and using the big nut on the pully OR by letting the engine turn over step by step against the transmission repeatedly apply the air to check the leakdown past the rings at about 15 degree steps of the crank, this will give you an indication of oval worn bores which means its pretty much time for a rebuild.

ok, I checked out the pump and sure enough as the previous owner said it appeares brand new also threw a hose into every orifice and there seemed to be no water restrictions.

I have now taken the head off and cleaned it up ready to get it shaved and tested, I figured it would be a nice thing to have done anyway.. I could not clearly see where a water breach could have been occuring but there was an abnormal, burnt sort of look between the 2nd and 3rd cylinders, I suppose will know for sure when the test has been done.

at the end of the day I only payed 1,800 for a 96" 300tdi disco that only has 174,000 k's on it so I dont mind spending a little more, I will also do the timing belt while I wait.

I will let you all know how it turns out.

cheers.

Head pic:-

thats a pretty good indicator of a delaminated head gasket.

hmm, after closer inspection I have found 2 small cracks coming from my glow plug ports in cyl 2 and 3, im hoping this is not an area of critical structural integrity, if so I wonder if I am able to get the ports drilled to stop the cracks from growing any further.

pics provided:-