tr3a overheating

[william]

Hi all

Over heating problems with my tr unable to go further than a few miles up too 200fh. flushed etc and thermostat removed.Steam water from overflow just want confirmation that head gasket has gone before I take head off.Dave

[RogerH]

Hi Dave,

welcome to the forum.

 

Have you done a compression test or a leak down test.

If you have a boroscope a look down the spark plug hole may show a super clean piston crown.

There is a test you can do for combustion gases in the radiator header.

 

Stuck closed thermostat

 

Easy enough to take the head off for 'the positive check.

 

Roger

Edited July 3, 2016 by RogerH

[Don H.]

A number of possibilities before the head gasket. Roger gives some good starting points.

 

Is this a brand new problem? How many miles on the engine? What kind of driving leads to the problem (slow stop and go or steady higher speed running)? How full is the radiator to start? Any overflow bottle fitted? Timing/mixture OK?

[AndyR100]

I use one of these to check :

 

http://www.frost.co.uk/block-tester.html

 

....... Andy

[foster461]

I use one of these to check :

 

http://www.frost.co.uk/block-tester.html

 

....... Andy

 

and what did the test reveal Andy ?

 

Stan

[AndyR100]

Confirmed that I did not have HGF on my old Stag, confirmed that a friend of mine did have HGF.

 

I havnt tried it on the TR as I have no warning signs - although I could do just for kicks.

 

...... Andy

[Don H.]

 

and what did the test reveal Andy ?

 

Stan

 

It's a pretty simple test, based on the principle that CO2 produced by combustion is weakly acidic when dissolved in water. The indicator solution shows slightly acidic coolant pH if combustion gasses are entering the cooling system.

[william]

Very few miles since total rebuild about 5-7 years ago local road use but the foot goes down when i am out in it.

Used today rad topped up drove aprox 3 miles had to turn back steam comimg out of overflow pipe no sign of water in rad ounce

cap taken off.

[Don H.]

My car overheated like crazy for the first 500 or so miles after a rebuild on the engine, including 87mm pistons and liners and slightly hotter cam. It would puke coolant especially in slow speed stop and go driving. It's seemed to have settled down after a few thousand miles, although it still likes to run hot. I fooled with a lot -- the main effects in helping resolve the issue were, I'd guess, (1) refitting the overflow bottle my car had since near new so coolant could puke into the bottle and siphon back into the radiator on cooling, (2) fitting a 6-bladed tropical fan to improve airflow at low speed -- many people here and in the greater TR world have thermostatically operated electric fans and speak highly of them, and (3) putting more miles on the engine.

 

Other factors that may or may not have helped included (4) carefully adjusting mixture and timing to make sure it wasn't lean and too advanced, (5) adding Water Wetter to the coolant -- one of those snake oil products that really does seem to help, (6) refitting an original brass radiator in place of the aluminium replacement originally added during the restoration, (7) refitting a bypass sleeve style thermostat -- although others have inserted a restrictor orifice in the bypass hose, which seems to work just as well with the flexibility of using a standard t-stat, and (8) putting on a different but otherwise identical radiator cap.

 

You're running a 4-psi long-reach radiator cap, yes? Higher psi probably won't work well on a sidescreen car and the wrong reach will definitely lead to boiling over as the system won't hold any pressure.

Edited July 4, 2016 by Don H.

[Lebro]

Stuck thermostat ?

 

Bob.

[RogerH]

Hi Dave,

did you retorque the head 500 miles after the last rebuild.?

 

This is not always done but is essential.

 

Roger

[Dave Larnder]

Dave

 

If the head gasket has gone, there will be water in the sump giving an emulsion on the dipstick. If unsure, drain the sump, but catch the oil in a large flat basin type thing, if clear replace the oil and breathe easier, the gasket ain´t gone.

Have you installed an air intake duct behind the grill to the radiator? a very worth while mod and easy to do and cheap.

If you have a balance tank (overflow bottle) put the 4lb pressure cap on the tank and a 0lb cap on the radiator.

 

Dave

[RogerH]

Hi Dave,

not a 0lb cap on the rad otherwise it will continually blow.

 

Anything bigger than the expansion tank cap or a fix cap.

 

Roger

[Red 6]

You will not like my contribution but here goes.

 

From your description and assuming that:

 

1. The radiator cap is pressurising the system

2. All the hoses are properly clamped (otherwise the system will not pressurise

3. Your head gas gate is is not leaking

4. You do not have an air lock in the cooling system

 

It sounds like you could have sediment/concretion at the base of no4 cylinder.

 

It this is the case there is no cure other than removing the cylinder liner and chipping out the debris.

 

It happened to me and I tried everything including all the usual old wives tales and miracle cures that popped up.

 

All the cylinders were removed along with approximately a coffee jar full of rusty debris and a new set of liners and pistons fitted

 

It was done with the engine in situ and did not cost much to do in parts or time.

 

One final test could be to fill the engine and open the block drain cock, water should flood out, if it trickles.............

[Bobbie]

Some very useful advice already given, most of which I checked when my then recently restored TR2, overheated with almost no provocation. It used to drive me nuts, recored radiator, ceramic coated manifold, wrapped exhaust down pipe, water wetter et-al made almost no difference.

On the advice of a fellow enthusiast, I removed my driving lamps and badges from the badge bar, hey presto! Instant resolution!

 

I appreciate this is a TR3a with different shape apron, but check the cardboard cowl to the radiator is intact, and remove any obstruction that may interfere with wind flow.

 

Regards Bob.

[Mart O]

My 3A had done very few miles since a rebuilt engine many years ago. Electric fan, on a thermostat, rather than std fan. Last year I suffered overheating each run. Over 20 miles, I would have to stop, to avoid it getting too high. Ths winter I spent a few days working through the cooling system and sorted it. I found:

- Electric fan cut in was unpredictable. I changed thermocouple and thermostat electric box and adjusted it to cut in marginally above normal.

- Coolant only trickled out of the engine tap. I removed it, used a two stage flush chemical treatment (Holts), attached a garden hose to flush the block and heater matrix (not at high pressure) and was amazed with the initial colour of what came out, even though it had been replaced 18 months before. Whilst flushing, used an old electric wire to fish around the block behind the tap and fully cleared to a decent flow. Replaced coolant.

- Recored the rad. This was the most expensive job, but there were some signs of impact damage to the thin veins over the years, so worth doing.

- Replaced the hoses & fixings, including the heater circuit and the bulkhead joint pieces, which were corroded, for peace of mind.

- Replaced the thermostat with an original type bellows (bypass sleeve) version, which immediately failed. Either it was poor quality, or the housing the thermostat slots into was just too rough to allow smooth operation. Anyway, I lost confidence in the bellows type and went back to a (new) non sleeve thermostat.

- To reduce bypass flow, inserted a washer into the bypass hose at the top end, secured with an extra jubilee clip.

- Removed a plastic overflow reservoir and siphon pipe, going back to the original drain pipe down to just below chassis.

- Replaced radiator cap with a 4lb version. The rad had come back from recoring with a new cap, which was 10lb!

- Finally, when I went to look at the TR Register stand at the NEC show, I noticed the TR3a on the stand has a device behind the grill which funnelled airflow to the radiator. This was missing from mine. I dont know if they are really necessary, but having done so much on the cooling, i thought what the heck. For c.£20 I bought, trimmed, painted and fitted a new fibreboard duct.

 

Now all works fine and no longer watching the temp gauge as much as the road. All basic stuff and having read previous queries on the forum. Don't know if it was any one thing, expect not, hope the list helps.

 

Martin

[iain]

I think its true to say that the 3a nose is the least efficient for cooling....the cardboard air deflectors are pretty essential.

Edited July 4, 2016 by iain

[rhino_mac]

I was told a 3a would overheat without the cardboard duct which is why Triumph bodged them in after the cars were sold. Mine ran appreciably cooler with it but still overheated until the engine rebuild.

 

I also had silting in No 4 cylinder when the engine was rebuilt. Stuart said there was almost no cooling to that cylinder at all.

 

My impression is that the 3a runs pretty hot and everything needs to be A1. Mine now runs lovely but I did new water pump, hoses, thermostat, ducting, radiator and flushed the block completely when it was rebuilt. It now runs just over the first mark on the thermostat reaching the middle mark in traffic on a warm day.

 

Before this, it would run just over the middle Mark and boil over when it reached the third mark and you turned the engine off.

[Dave Larnder]

Hi Dave,

not a 0lb cap on the rad otherwise it will continually blow.

 

Anything bigger than the expansion tank cap or a fix cap.

 

Roger

 

 

Hi Dave,

not a 0lb cap on the rad otherwise it will continually blow.

 

Anything bigger than the expansion tank cap or a fix cap.

 

Roger

Hi Roger

Agreed, I only said a 0lb cap as opposed to a fixed cap so our member would put the 4lb one on the tank, not the rad. It is surprising how many owners did not know that. I have a custom built overflow or balance tank with the 4lb on it, I don´t know how anybody manages with a bottle, Wonder what holds the pressure'

 

Dave

[william]

Thanks to all who replied lots of things to ponder over head not coming off just just yet.

[RogerH]

Hi Dave,

the TR4A with the expansion bottle only works because of the special double sealed rad cap.

 

The upper seal seals the system from the outside - it is fixed.

The lower seal is the pressure seal. At a certain pressure the seal lifts and sends excess water/steam into the bottle.

The bottom of the pipe in the bottle is below the level of the standing water in the bottle.

So the overflow water goes into the bottle. If the water level in the rad backs off it will suck fluid out of the bottle. Eventually the lower seal will close.

 

Simple in an odd way.

 

Roger

[peejay4A]

Just to add to that, the lower seal is in two parts. One opens upwards with coolant expansion to allow excess into the overflow bottle. The other opens downwards under cooling to allow coolant to be drawn back into the radiator.

Edited July 5, 2016 by peejay4A

[Lebro]

_{Just to add to that further !}

_{The "out" seal opens at 4PSI, the "back in" seal is simply a one way valve, & requires only a tiny pressure difference.}

 

_Bob.

 

_P.S.

 

_{This is the system I have on my TR3, only snag is it's hard (impossible?) to find the rad cap with the top seal in the length required for the TR3 rad.}

_{I modified my standard rad cap by removing the thin metal "seal" (not really a proper seal), & replacing it with a home made cork one.}

Edited July 6, 2016 by Lebro

[Dave Larnder]

Roger

 

On the TR4 rad. how far below the cap is the normal fluid level?

We all know the level on the 3A cap is a little above the bottom of the neck, but with my overflow tank, the water is always up to the bottom of the cap, and if draining and refilling the system, I fill it to that level not the old standard one. I check the level in the tank regularly when I get home and cool down, and it is always at the same level, so the system is not putting that extra fluid into the tank, the bottom of which is above the level of the rad top, it sits in the space for the RHD pedal box.

 

Dave

[roy53]

When you have tried the easy items ,thermostat,rad cap and whilst doing this use a block and wet and dry paper to on the top of the rad to ensure that it is flat.

 

I tried all types of rad flush,felt for cold spots etc to no avail. Borrowed a rad from another and solved it so a recored rad did the trick.

 

ROY