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Symptons of head gasket failure

Rust Restorer

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Today I worryingly had the symptons of head gasket failure on the way to work, the wife called me around 5 minutes after I set off, so pulled over to take the call, the temp gauge shot up, but fan did not come on, As I pulled away it went right down again, so just kept an eye on it. After I pulled in at work I noticed a stream of water, investigation showed it coming out of header overflow, so I released cap and more came out. Let it cool down a bit, then at break time had a look, put more water in and it did the same again. First thoughts back pressure through gasket failure. So left it till dinner time. After having thought about it and talking to Rick at S and S I hoped air in system, not head gasket, so I took of the thermostat cover, filled system through there, put back the cover but left thermostat out, ran up to temp as best you can without thermostat, then re-fitted thermostat and ran again. All seemed OK, but as I had not tested thermostat I later took this out before driving home.
Tonight I have totally drained it, flushed it,  and  re -filled, tested thermostat, opens and closes but not sure of temp, (wife would not let me use cooking thermometer) so will change anyway.
Had a test run, did not push any water out. No signs of oil in water, oil seems OK. Temp normal, fan does its job ok, Head torqued correctly.
My thought, I had the front end jacked up for a couple of days at weekend, I wonder if this could have caused a large air lock?
Any thoughts?

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Rust_Restorer wrote:
... pulled over ... the temp gauge shot up, but fan did not come on ...

First check your fan. Sounds like it doesn't 'switch on properly.
That's why I stick to the original set up  ;)
I have never had air in my coolant systems in 22 years of TR7 motoring, so not the first thing I'd worry about

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just uneducated guesses so don't shoot me for talking gibberish!

If it was a head gasket problem, you would either;
1- lose water into oil system, which would show as a creamy whitish emulsion
2-lose water into cylinder which would leave the exhaust as steam - not always obvious but loss of water should be
3- pressurise the water system which would cause water to 'blow' off (The same symptom as the water overheating)

If none of the above, then maybe you just overheated, especially if the fan didn't come on? However it wasn't a particular hot day?

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Speaking of the TR7 4-cyl cooling system, I have some questions on that...

I live in the desert and during the summer it gets up to about 110F - I don't plan on driving my TR7 that much during that time, but probably will on occassion. I'm planning to go ahead and rebuild my engine and wonder:

  • Should I have the existing radiator rebuilt/fixed or should I buy a new one that is larger? Would a larger radiator cause the water pump to work too hard and possibly fail early?
  • Should I stick with the existing original fan, or go with electric ones?
  • If I stick with the original, is there any benefit (or way) of using a fan shroud?

Thanks for your advice.

Here's a shot of my nasty radiator, etc.:

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I have been using the standard cooling system on my TR7's for over 20 years now.
And as long as everything is in good working condition it should be OK.
Even with very hot weather (which sometimes occurs even here) I’ve never had any problems

Make sure you use proper coolant (the one that doesn't need mixing with water).
And make sure the radiator doesn't have any blockages.
If in doubt replace or recondition, whatever is the cheaper option were you live.

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So far I have not had a repeat of this. I have now changed thermostat, which upon closer inspection does not close properly. I believe that as I had the front of the car jacked up all weekend, perhaps letting air in the system from a slightly leaking hose at radiator (works both ways doesnt it? ie if it leaks water, also lets air in?) combined with the dodgy thermostat allowed water to get hot quicker at the top of the engine, with air lock pushing water through to expansion tank, via partiatally open thermostat.

When I originally stopped I had not being going long enough for Fan to cut in, it is the kenlowe copper bulb type in the rad top tube,  (a slight leak here I have never cured) whereas the temp sender is in the header tank and probably reacts quicker to temp change.

Gonna keep a close eye on it.

On the head since re-build I have a couple of Industrial type Temperature Indicator Strips, the type that change colour permanently with higher temperatures, can see no change in these, so I dont think overheating here an issue. But again, keeping a close eye on it.  Touch Wood.

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  • 3 weeks later...

B----r, no longer symptons, now confirmed, took the car over to Anglian Triumph for Dave to do a gas check on the coolant. Whilst not a full blown head gasket failure, ie steam everywhere, the test kit did change colour from blue to green indicating gases in the coolant, possibly a slight bridging between the gasket on cylinders, maybe a warped head. So off with its head! Water pump check and pressure check will also be carried out at same time.

Being a saddo who keeps a log book, I worked out that since back on the road after rebuild on 30/04/03 the head has lasted for 26116 miles.
Statistics show first few years, very low miles, then I joined Club Triumph 3 years ago and mileage shot up!!!!

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Statistics show first few years, very low miles, then I joined Club Triumph 3 years ago and mileage shot up!!!!quote]

You just can't trust low mileage cars, my Volvo had done 495,000mls, Mercedes 301,000mls and the Peugeot (hate to admit that) 299,000mls, never went wrong, and the Volvo was still going last time I saw it ;)

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Thanks Beans. Another question on heads, since that seems to be related... I've got manuals that show the head bolt torque pattern and torque settings, so my question to those of you who may have rebuilt a TR7 4-cyl: do you do a partial torque following the pattern, then go over the pattern again and bring each head bolt to proper torque spec? Or do you torque to spec the first time you hit each bolt as you go? I hope that makes sense. I'm thinking that a partial torque through the pattern with a to-spec torque the second time around makes some sense. Any thoughts? Does it matter?

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Manual only mentions the torque sequence and settings.

I usually start with “tightening” all studs and bolts in the prescribed sequence,
but with the lowest setting on my torque wrench (approximately 20 Nm).

After that I torque them down as per the book, working from the centre outwards.

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