Sprint Water Circulation/Pressure Problem

[James R]

Hello

I am posting this thread in the hope that someone more of an expert than I can help me with questions I have around a cooling issue. I apologise now for the long thread…

So my Sprint seems to have a water circulation issue, resulting in a heavily pressurised system under standard idling. (My car is not on the road and it is a 74 Sprint). So what do I have..... standing at the front looking into the engine..

Top Left Rad Hose Warm
Top Right Hose Hot
Bottom left Rad Hose Hot
Radiator Hot
Right hand Heater hose at H pipe cool/cold. This is from the water-pump
Left hand Heater hose Hot
Heater was working fine and then it wouldn't.
Large radiator hoses bulging (have pics) so had to turn off and let cool down
Temp gauge just over middle at this point.

I have tried changing the stat to no avail.
I have tried with no stat, same.
I have following previous advise, removed the inlet manifold and water pump cover thinking that the water pump may be at fault. Water pump impellor is in excellent condition, with no marks, or wear. looks very good. To see if it turns on the jackshaft I have turned the engine manually and the pump moves round, albeit it is hard to crank the engine by hand using the pulley. I am thus assuming that the pump operates.

So what I would appreciate some assistance with please is:

1. Am I right to assume that because the pump rotates by hand that it is in good working order or do I need to remove it for further review/evaluation? (the impellor cover isn’t loose or spinning when you try to move it by hand so it hasn’t become detached from the rest of the pump I don’t believe)
2. I am assuming that the radiator is circulating and isn’t blocked because it gets Hot. Stupid question I know but worth checking, I have also flushed it with a hose both ways.

I think this leaves me with the possibility of the head gasket.. is that the only remaining possible conclusion? And if it is then is there any way in which I can check to confirm it?

And lastly if it does turn out to be the head gasket then does anybody recommend a specialist who could repair it for me?

Thank you in advance for any help/Assistance/guidance. I don’t get much time to tinker with the car but really want to make an effort to get her back where she belongs and there is a bit to do!

[yorkshire_spam]

You can get a chemical test kit that will test the coolant for exhaust gases - probably worth a punt about about 25 quid just to check before people start removing heads?

Is the flow of water through the rad when flushing "free" ?
Is the rad a "known good one" ? By that I mean, is it the right number of rows and correct thickness for the sprint engine?

Can't comment on the water pump - I'm no expert in that area.

[Galileo]

The pump cannot create enough pressure to make (good condition) hoses bulge, in my mind only two things can do that, pump not working or able to circulate due to a blockage and so steam created around cylinder jacket, or a head gasket failure as my northern friend above suggested. Any potential blockages are easily checked with a hose pipe.

[James R]

Thank you both for taking the time to respond. it is much appreciated and apologies for further questions...

in checking car for blockages i have already done that, but will check again. Pushing water through the system via the thermostat housing with a hose, leaving off a bottom exit rad pipe would suffice i assume?

In using a test kit i assume that i wont need to add antifreeze, and just water would be sufficient. and i could leave the thermostat out as well?

Also in the absence of a radcap, i assume the small hole at the top of he thermostat housing would be the place to locate the probe?

FIO hoses are all in good condition and the radiator was brand new many years back and it was for a sprint. it has been in the car for a while with no trouble and it is only in recent times that the pressurisation has occurred, which considering what you have both said, looks more and more like the head... not good news!

Thanks again

[yorkshire_spam]

The test kit comes with a rubber bung that you just shove in the top of the header tank (or similar)
If you are in the West Yorkshire area you are welcome to borrow mine - I have plenty of fluid left from testing the 1850 HG.

Extreme pressurisation would tend to point at HG failure or something like that. Sorry.

[GTS290N]

Do not run slants (Sprint, 1850, TR7) without a thermostat, you will overheat the system. The stat operates opposite to 'normal' stats.

[James R]

Thank you 'Yorkshire Spam' for the offer. your quite a way from me as i am in berkshire so i will see what i can obtain here.

it is looking more and more like the dreaded HG.... but i will do the tests to confirm the potential theory..

If it does turn out to be the HG, is there anyone that could be recommended to undertake the work? i wouldnt want to hand it to someone not recommended. been down that road many years back with other aspects of the car...

Thanks again to all..

[Carledo]

The thing that disturbs me about your symptoms is the cold heater return hose to the pump cover. This suggests to me that the heater tap or radiator is blocked or the tap is not functioning correctly, ie cable not operating. Any or all of these could result in air locks forming in the heater hoses and consequent overpressure. The stat MUST be working if the rad gets hot. If you're experiencing bulging hoses, i'd invest in some new ones, the ones you have are weak and WILL fail!

Of course, a HGF could also give your symptoms, but check the heater out properly first, it's a lot cheaper!

Steve

[ab1]

Hi

Might not be your issue but i had a similar thing on my 1850, the hoses were under a lot of pressure even with the engine at normal temperature.

It was the outlet on the thermostat housing that connects to the pipe to the expansion bottle, it was blocked so there was nowhere for the pressure to expand into. When i took the top off the expansion bottle the pressure was still in the hoses.

The small metal pipe that the rubber hose joins onto was totally blocked with a toothpaste consistency paste once this was cleared it was just normal pressure in the hoses.

Alan

[Carledo]

Hi

Might not be your issue but i had a similar thing on my 1850, the hoses were under a lot of pressure even with the engine at normal temperature.

It was the outlet on the thermostat housing that connects to the pipe to the expansion bottle, it was blocked so there was nowhere for the pressure to expand into. When i took the top off the expansion bottle the pressure was still in the hoses.

The small metal pipe that the rubber hose joins onto was totally blocked with a toothpaste consistency paste once this was cleared it was just normal pressure in the hoses.

Alan

Mahesh had this exact problem with his Sprint. Because the pressure couldn't escape in the normal way, it kept leaking past the water pump! By the time we sussed what was wrong and fixed it, Mahesh had overhauled the water pump about 4 times!

Steve

[James R]

Thank you very much Steve et al for the information. Really Really appreciate it.

I will have a look at that feed and also the pipe that runs to the expansion tank to check for blockages, along with checking/flushing again the rad, maybe renewing the hoses and buying a HG test kit if the issue still remains. So a few bits to be getting on with once I put the manifold etc back together.

Thank you all thus far for your help and time.

[MIG Wielder]

Hi James, Sorry to hear about these problems. Just to add to what has been said ..you need the thermostat with the protuding foot that operates when it is hot. Adverts that say "fits Triumph Dolomite " . Well yes it "fits" but may not work as intended.
Here is why as illustrated by Iain Sprint95m on here.

One other thing worth doing is ensuring the small hole in the thermostat housing is clear. It goes to the smaller bore pipe to the top RHS of the radiator. I think this is an air bleed to allow air to escape. This hose should be full of water if disconnected briefly.
Interestingly, this bulging of the hoses you describe are typical of head gasket failure. I had exactly this on both Sprints and most recently on the 1850, particularly has the heater is running cold. But yes do have a look at the heater hoses / valve first.
Tony.

[James R]

Thank you all again for your help.

I have looked at the thermostat housing and the small hole was indeed blocked with gunk along with the expansion pipe, which was a solid-ish mass of gunk. Albeit one was difficult to get to, I have cleaned these out completely now such that water flows freely from all orrifice's of the housing. So my intention is to buy the parts i need to reassemble manifold/water pump housing/radiator etc and fill her back up and see what happens.

I will advise of the outcome as soon as this has been done. Again thank you to all who replied, it is very much appreciated, and fingers crossed!

Br

James