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bblehead

Help with massive overheat

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Hi all just went out for a quick spin about 4 miles. Never checked the temp gauge and car was running perfectly.

As I came up my driveway there was a pop and a big puff of steam from under the bonnet. Coasted to a stop and switched off the engine and opened the bonnet.

Steam and crackling g noise coming from the oil filler cap and hose blown off the expansion bottle cap. Released the cap, no pressure or very little and no water evident. Removed oil filler cap and steam is coming out. Checked the sump oil is clear but way over the max mark . Advice before I start stripping g it down would be welcome, sounds like head gasket but I would appreciate advice as I am pretty unfamiliar with the engine. Thanks in advance

 

 

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It may not be the head gasket. There is a core plug in the top of the head inside the rocker cover which can fail and give these symptoms - there was a recent thread on it. Worth taking the rocker cover off and looking before doing anything else. 

If the plug is intact this thread may help:

 

 

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Agree with Rob

review this thread about the head core plug inside the rocker cover

Take your rocker cover off and refill the radiator with water.   Does water shew on the top of the head?

Peter W

 

Edited by BlueTR3A-5EKT

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Curses batman, the plug is in top condition, ran the engine with the rocker cover off as oil level although high was not showing any water. Topped up the coolant resevoir as well. Engine ran fine, clean oil coming from rockers, 50psi oil pressure but no water from the core plug. Let it run for 5 mins and it started dribbling water from the reservoir cap tell tale, when I switched off this turned into a full bore discharge, temp gauge had Not moved.

Not sure where to go next to be honest. I am wondering if the big puff of steam was the rad cap hose being blown off when it lifted and the steam I saw from the oil filler was condensation in the oil and head being boiled off (grasping at straws) as the temp soared. Half tempted to drain it refill it and run it up to temp.

 

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You may have had an air lock after re-filling with water which might account for the full-bore discharge and no indication on the gauge, so that might not be relevant.

I would be wary of running the engine again until you have found out why the oil level is so high. The oil will float on top of water so it wouldn't show on the dipstick unless there is an awful lot of it but if any is there the oil pump might pick it up.

How about draining the sump as a starter to find out what is in there?  (If it's just oil you can even put it back in again to save waste.) 

A compression test should show if the gasket has gone and if so, which cylinders are affected.  

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4 hours ago, bblehead said:

Hi all just went out for a quick spin about 4 miles. Never checked the temp gauge and car was running perfectly.

As I came up my driveway there was a pop and a big puff of steam from under the bonnet. Coasted to a stop and switched off the engine and opened the bonnet.

Steam and crackling g noise coming from the oil filler cap and hose blown off the expansion bottle cap. Released the cap, no pressure or very little and no water evident. Removed oil filler cap and steam is coming out. Checked the sump oil is clear but way over the max mark . Advice before I start stripping g it down would be welcome, sounds like head gasket but I would appreciate advice as I am pretty unfamiliar with the engine. Thanks in advance

 

 

Hi,

Expansion bottle cap !!!  is this no ordinary engine !!?

 

Roger

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This is posted in the sidescreen section TR 2/3/3a and they don't have a separate overflow expansion bottle, they have the extended neck radiator with the expansion chamber incorporated. Either this car has had a TR4a expansion bottle fitted or some other contrivance.

I'm with Rob, sounds like an airlock in the cooling system maybe caused by a stuck thermostat. Follow Robs advice, sounds good to me.

Mick Richards  

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What is the coolant level about after one day doing nothing?

I would put the spark plugs out and look for coolant there.

After this gives you no information I would put the thermostat out and test it in hot water.

Edited by Z320

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5 hours ago, RobH said:

A compression test should show if the gasket has gone and if so, which cylinders are affected.  

Will a compression test show anything if it is only a small blow?

Rgds Ian

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Well perhaps water in the oil (if that is what it is) doesn't sound like the result of a small blow Ian ? :blink:

At this stage I think any simple diagnostic is a help rather than stripping the head off maybe unnecessarily. 

Edited by RobH

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If your oil level has increased there is water in the oil. Oil levels do not go up on their own. 

Do not run the engine. Drain the sump and see what is there. If the engine overheated you may have cooked the oil and it needs to be changed anyway.

If there is nothing untoward it is possible you overfilled the oil and forgot, or were checking it on a surface that wasn't level.

If there is water in the sump it will be the head gasket if the core plug is OK. Not usual but it is remotely possible that you have a cracked head or, worse, a failed figure of 8 joint.

The hose coming off may have been a consequence of the overheat rather than the cause.

Again, do not run the engine.

Edited by John McCormack

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When my figure of 8 seals failed the oil level increased with tell-tale cream emulsion in the rocker cover but I don't recall any severe overheating but I had wondered why the water needed topping up the week before.  Any gas bubbles seen in the header tank when the engine running?

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Drained the sump,about a quarter to a third of the inventory was coolant with the oil sitting on top unfortunately. Coolant was still blue strangely and there was no mixing or mayo but obviously I have a real issue to resolve. Appreciate the help, will have a think on my options to get back on the road.

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