thermostat directional?

[sforster]

Can anyone tell me if the modern replacement thermostats are directional as they seem to fit either way and it seems the first place to start because the car is overheating.

Simon.

[marvmul]

The part of the thermostat containing the wax should face to the engine, it must be immersed in the water that is circulating in the engine when the thermostat is closed.

[stuart]

Can anyone tell me if the modern replacement thermostats are directional as they seem to fit either way and it seems the first place to start because the car is overheating.

Simon.

Simon be aware that the modern thermostats dont have the sleeve on them to cover the bypass outlet so they are not as effective. Unfortunately the original type are now getting expensive and difficult to find in the correct temperature range.

Stuart.

[sforster]

Marvmul,

I can't find any wax. On one side of the thermostat is the spring and plunger which I think is the engine side is this correct? Thermostat opening into the engine side.

Simon.

[Nigel Lay]

Simon, as Stuart said watch out if you are fitting a modern replacement. The originals had a sleeve that virtually shut off the bypass hose when it opened. If you just fit a modern stat most of the water will just flow round the engine block and not the radiator (getting hotter & hotter in the process). Look at previous threads about partially blocking off the bypass hose etc. As a side matter TS952 runs without a fan and I have only had to use the electric fan twice while stationary in traffic last summer, it is fitted with an 'original style' sleeved stat. I will email a chap that had loads for sale and put them on ebay a couple of years ago to see if he has any left.

Nigel (with TS952)

[mikew]

Simon, as Stuart said watch out if you are fitting a modern replacement. The originals had a sleeve that virtually shut off the bypass hose when it opened. If you just fit a modern stat most of the water will just flow round the engine block and not the radiator (getting hotter & hotter in the process). Look at previous threads about partially blocking off the bypass hose etc. As a side matter TS952 runs without a fan and I have only had to use the electric fan twice while stationary in traffic last summer, it is fitted with an 'original style' sleeved stat. I will email a chap that had loads for sale and put them on ebay a couple of years ago to see if he has any left.

Nigel (with TS952)

 

It may be worth looking at some of the "modern" triumph stag replacement stats, these are now available with a sleeve to block the stag bypass system - I am not sure if it is the same. Southern Motor Spares are at least one supplier selling these in a number of temperature ranges

 

mike

[marvmul]

Marvmul,

I can't find any wax. On one side of the thermostat is the spring and plunger which I think is the engine side is this correct? Thermostat opening into the engine side.

Simon.

That is correct. My explanation was not clear indeed. The wax is in the housing surrounded by the spring windings.

Take the advise of Stuart and the others about the modern replacement thermostats.

TeriAnn Wakeman's webside has an article about the modern thermostats without the skirts : she explains how to restrict the bypass hose with a washer or something to reduce the diameter to 3/8".Click here for her very interesting website. There are furhter links to Net Nuggets with lots of technical articles about the sidescreen TR's.

[Andrew Smith]

Simon

 

I asked similar questions to you some time back after the engine rebuild on my 3A in November 03. My engine was rebuilt to 87mm with a lead-free head and suffered from intermittent overheating and air locks.

 

Given that the rad, pump, hoses and waterways are all ok, these are the measures that worked for me and are offered as general advice:

 

1. Cut out the centre mechanical parts from a modern wax type thermostat and fit it: this then acts as a restrictor and backs up the water allowing it to cool in the rad. Without it, the water would just pass through the rad limiting cooling affect.

 

2. Fit a restrictor in the bye-pass hose; otherwise the water will just circulate and "bye-pass" the rad for the most part. Without the restrictor there is a chance of creating local hotspots in the engine with consequent results!

 

3. For the restrictor, I used a washer with a 1/4" hole (GHF314 from Moss is ideal) or you could use a 10p piece and drill it with either 1/8th or 1/4". You will need to use a second jubilee clip behind the washer to keep it in place and prevent it slipping down the hose under pressure. Ensure the washer/coin is fitted hard against the bye-pass housing outlet inside the hose.

 

4. Use Shell Opitmax with Castrol Valve Master Plus, this reduces run-on in my case.

 

5. Fit a Kenlow or similar. I fitted a 13" Kenlow Blower 2000 Series (13/B); this works a treat and fits neatly on the rad and is supported by the internal lip on the apron.

 

6. Definitely fit the rad ducting, this is often overlooked as discussed in other posts: it's a must.

 

7. Finally, ensure the correct rad cap is fitted: 4psi with the correct length neck otherwise water will just deposit itself under your car via the overflow tube. At one stage I was considering fitting the TR4 expansion bottle, but haven't ruled this out entirely.

 

With all these measures in place my 3A now runs at 170-180f with outside temps up in the mid-eighties and only in heavy traffic does the Kenlow need to come on now. I've set this at 185f.

 

Hope some of this of use. Good luck

 

Cheers

Andrew

Edited May 26, 2007 by Andrew Smith

[sforster]

Thanks Andrew and Marvmul,

I have carefully read and hopefully understood everything you are saying, though I think I should explain the circumstances. Rebuilt engine with 87mm pistons and fast road cam, also and my biggest area for concern is an alloy radiator. Today was the 1st serious test as I only got the number plates yesterday. By the way yes I have made a funnel/ducting for the air to be pushed through the rad. Todays air temp 23-25C. After 4-5 kilometers the temp went above 185, no traffic infront and engine running less than 3000 revs approx 60mph, when I returned home, open the gates stop/start the gauge was around 3/4+ and on turning the engine off the rad cap released and dumped about a litre of water. I have repeated the journey and same thing, when I removed the thermostat to check it yes it is the correct way round, also flushed the rad, this seems ok? Have tested the 'stat in hot water and it opens.

On the 3a I had prior to this car the set up was the same though I had a kenlowe and standard rad. The kenlowe was operated by a manual switch and only used on long hills or when the air temp was above 30+C. I can't help thinking the problem may lay with the alloy rad though I will now try the methods you have described.

Simon.

[Andrew Smith]

Simon

 

Is your bottom hose cool/cold when the engine is running to temp, or overheating?

 

If so, it sounds like you may have nothing more than an air lock in the system, I was plagued by these and my car also dumped water all over my drive. A simple fix is to jack up the front wheels and run the engine to temp without the rad cap fitted and watch for air bubbles at the rad filler neck. Let the car run for about 10 mins and then refit the cap and feel the bottom hose for temp - you may have to do this several times.

 

Cheers

Andrew

 

PS, newly rebuilt engine do tend to run hotter for a couple of thousand miles or until they have been run in.

Edited May 26, 2007 by Andrew Smith

[sforster]

Andrew,

All the hoses are hot when the engine is up to temp, heater works fine this is why I am worried that the problem is the radiator. Tomorrow I will try addapting the thermostat and making a restrictor valve.

Simon.

[marvmul]

Simon, you can try and do not refill when the engine has dumped water after the first journey.

The radiator should not be completely full, only a little above the core : when turning off the engine, coolant can be displaced from the engine to the radiator without much rising of the pressure. After cooling down, localised steam in the engine will become fluid again and coolant will return from the radiator to the engine.

[brydon]

Hi

 

Are you sure your temp gauge is accurate?

 

I recall you can buy some tape that attaches to the engine, and will indicate an accurate temp.

 

Just a thought.

 

Keep TRing

 

Brydon

[sforster]

Anyone got a box of matches! This morning cut down the thermostat removing the moving parts and made a restrictor for the by pass pipe, and off we go thinking this will cure the problem. Exactly the same, no difference at all. Well as far as I was concerned the only thing left was the radiator, so off came the front of the car, out came the rad and hello perhaps the fan belt should be a tad tighter as I could have used it as a catapult. There was I surrounded by my recently painted pride and joy thinking I've just won di__ head of the year award. OK I thought I'll keep this one to myself. Flushed out the rad happy that I'd found the problem albeit embarassing, I'd already cleaned the brass rad ready to fit but by now I'm thinking alloy, go on you know it makes sense. Back it went and after putting the car back together, lining the apron up, fitting the impossible to fit grill I'm off down the road into the early evening sun. You cannot imagine my disbelief when the gauge carried on past 185 and upto 200.

Has anyone had experience with alloy rads and does anyone want one, though I won't garantee it will be in one piece. I really can't think what else could be causing the car to overheat.

Simon.

[marvmul]

Do your car has a wide belt? A wide belt has to be fitted with a lot of slack, it will not slip.

A year ago I went almost crazy by an overheating problem : in the end it was the impeller : it was a loose fit on the spindle : I did not find the problem till the impeller was very loose : it was a new pump : at the first run, it took about 15minutes before the engine overheated : the impeller still rotated, but slower than the spindle. In the end the gauge got to over 100° C after only 2 minutes stationary running : by then the impeller didn't spin but verly slowly I suppose.

If the alloy radiator isn't clogged, don't discard it, the cause of the overheating is elsewhere.

Did you check the ignition timing : when this is far out, it can cause overheating.

As I said, dumping 1 litre of water after a run, when the raditator is almost filled to the top, is no reason for concern.Do another run without topping up the radiator.

185 - 200 ° is high, but still not dangerous. On my TR3A, when I remove the filler cap while the (hot)engine is still running , it will not dump any coolant, but it will dump coolant when I remove the filler cap AFTER switching off the engine (local hot spots makes steam pockets in the engine).

[sforster]

Marvmul, the belt is a wide one so perhaps needs a bit more play in it, the ignition timing and carbs have been set up correctly and the engine runs fine, mixture is ok as the plugs are a good colour. I tested the compression today as the head was skimmed and addapted for lead free fuel, compression on all cylinders was 150. The water pump was a new upgraded pump with an external grease nipple, as the water is circulating around the engine without any problems I assume the pump is good.

Simon

[marvmul]

As the engine has been rebuilt, I assume that it is clean : no scale and other swarf around the liners and in the cylinderhead.

The engine runs rather hot, but is it really overheating?

Maybe it will run cooler after running in? An air lock can be difficult to get rid off sometimes.

Another thing to consider is the distance between radiator and ventilator : the efficiency of the ventilator is diminishing rapidly with greater distance. Maybe the alloy radiator is thinner and/or fitted more to the front of the car?

[sforster]

The alloy rad is actually thicker than a standard rad, is located in the same place therefore possibly 1/4" nearer the fan. I did wonder if the alloy rad requires an electric fan to ram more air through it but at 60mph there should be enough air being directed through to the rad. The engine has been cleaned prior to reassembly and all care taken to make sure it remained clean during assembly. The temperture is rising too high and when the car is running at a steady speed without traffic infront, it struggles to stay below 3/4 so when you stop or slow down it very quickly gets too hot. Under normal use and conditions the car should run at 185+/- this isn't the case here.

Simon

[marvmul]

I can't say much anymore!

Perhaps, as you are suggesting, an electric fan will bring the temperature down, but the standard engine fan should be enough.

What kind of u/r pump is it? A year ago, I ordered an u/r pump with an impeller with 6 curved blades instead of 4, at Cambridge Motorsport : Jon Savage answered that he didn't sell them anymore because they were unreliable. He didn't say in what respect, but because the obvious reasons for overheating are ruled out, it would not be silly to check if the impeller isn't moving on the spindle : I experienced this on 2 new aftermarket standard pumps.

If the temperature gauge gives a wrong reading, it's alway too high, because of the construction :when the spiralled tube has lost elasticity, the gauge readily goes to a high reading.

[stuart]

Simple way to check if the temperature gauge is reading correct is to immerse the bulb in a cup of boiling water with a thermometer in it and check to see if the readings correspond.Some of the aftermarket water pumps that were around for a while had impellors that werent deep enough to give much flow and caused cavitation inside the pump.

Stuart.

Edited May 28, 2007 by stuart

[Andy Moltu]

The alloy rad is actually thicker than a standard rad, is located in the same place therefore possibly 1/4" nearer the fan. I did wonder if the alloy rad requires an electric fan to ram more air through it but at 60mph there should be enough air being directed through to the rad.

 

The thickness depends which alloy rad you use. The assumption that more rows is better doesn't always hold true. (The thicker ones restrict air flow) The ones we had made for the Leicester group were no thicker than the originals however the fins were ribbed which increased the area to dissipate heat. (According to the manufacturer of the cores in Holland their 4 row alloy cores dissipate 20% more heat than the same sizes standard core - they make both sorts so no reason to disbelieve them)

 

There was/is also a big debate in Stag circles about 4 or 5 row cores - did 5 row cores perform less well because of their restricting airflow? (We also had some done for the Stags (we now have 4 in the group - possibly more than the Stag owners do) Certainly my 4 row alloy one cools the car much better than the standard rad)

 

Returning to your overheating - as the thermostat/bipass issue has been ruled out then either the core is silted/scaled up, the water pump not functioning or your engine is producing too much heat such as a blown head gasket or sunken cylinder liner. Have you done a compression test?

Edited May 28, 2007 by andymoltu

[Don Elliott]

Many of the chaps who race TRs have installed alloy radiators. After installing the alloy radiator, they report that all their over-heating problems dissappeared. And they don't use a fan - of any type.

 

When we were finishing the restoration of a TR3A last year, the temperature gauge went up to 220 and higher when it had been sitting at idle for about 10 minutes or less. We removed the radiator cap and put a thermocouple which was attached to a digital multimeter into the coolant. It read 180 degrees F. We did this test several times over the next few days, then we took off the bezel and glass front from the temperature gauge, bent the needle down to 180 and this solved the problem.

 

You can use any kind of thermometer, analogue or digital, bar-b-que or kitchen type, baby thermoneter or a medical one that you might stick under your tongue. Just clean it well after and don't tell your lady.

[Nigel Lay]

I agree with Don about guages reading over, the one on TS952 is the original and reads 12-15 degrees over compared with the real water temperature. The water level at cold is 1/4" deep at the rear of the filler neck, much more and it just blows it out. I have not topped it up in the last 500 miles. I did find in the first instance after the rebuild that if I overfilled the radiator it would blow it out and MORE BESIDES, I panicked thinking of leaking head gasket etc. but I think it was you Don that put me right by telling me to fill up so that the water just covered the base of the filler neck when cold - it certainly solved my problems.

DONT give up Simon, just think of motoring with the hood down, sun on the back of your neck and wind in your hair (I don't have too much of a problem with the last item)

Nigel

Edited May 28, 2007 by Nigel Lay

[BrianC]

It does sometimes pay to read the original handbook. In this case it says "...keep the filler neck of the filler at least half full of water".

Always worked for me (barring airlocks or faulty thermostats), although I usually erred on the side of less, rather then more, because whenever I topped it up it rapidly ejected it until the level was about 1/4-1/2".

I also did the same as Don when I cleaned up the gauges prior to reinstalling them. The temp gauge was over-reading but has been adjusted to read correctly. Just hope the rest of the system will perform as required.

Edited May 28, 2007 by BrianC

[Andy Moltu]

Many of the chaps who race TRs have installed alloy radiators. After installing the alloy radiator, they report that all their over-heating problems dissappeared. And they don't use a fan - of any type.

 

Racers don't tend to spend too much time in traffic jams! Generally the fan is not required when moving as the movement of the car generates sufficient airflow to render the fan almost insignificant in comparison.