Overheating

[Z320]

I wrote a very detailed post about the bellows thermostat with skirt / sleeve at the TR3 forum.

And the issue about the bypass and the difference from the TR2-4 and TR4A water pump housing.

In short words about the bellows with skirt: 

- it is more like a plug in the direction to the rad which forces the coolant through the bypass

- the sleeve / skirt cannot close the bypass, this is only wishful thinking since ages

- take a close look on that, forget all the stories and think yourself

- shure it was the best of its time until the wax thermostat was established 

BUT the bypass is needed to have always as much flow through the engine,

it is reduced on the waterpump housing to 8.5 mm on TR4A and to 8.0 mm on the TR6.

This in combination with a wax thermostat works lovely. I cannot recommend at all to reduce it more.

 

Edited June 19, 2020 by Z320

[stuart]

Thats right Marco you dont need a shrouded bellows thermostat on a 4 or 4a due to the housing change.

Stuart.

[BlueTR3A-5EKT]

1 hour ago, Z320 said:

I wrote a very detailed post about the bellows thermostat with skirt / sleeve at the TR3 forum.

And the issue about the bypass and the difference from the TR2-4 and TR4A water pump housing.

In short words about the bellows with skirt: 

- it is more like a plug in the direction to the rad which forces the coolant through the bypass

- the sleeve / skirt cannot close the bypass, this is only wishful thinking since ages

- take a close look on that, forget all the stories and think yourself

- shure it was the best of its time until the wax thermostat was established 

BUT the bypass is needed to have always as much flow through the engine,

it is reduced on the waterpump housing to 8.5 mm on TR4A and to 8.0 mm on the TR6.

This in combination with a wax thermostat works lovely. I cannot recommend at all to reduce it more.

 

+1

 

Peter  W

[Z320]

I want to bring my post on the TR3 forum to its end as soon as possible,

the only thing I need is one hot summer day.

Edited June 19, 2020 by Z320

[JJC]

Thanks for the posts. There is a YouTube video showing the bypass blocked completely (WEGS Garage, TR4 overheating). But I take it from Marko that some flow is required. So with a non bellows thermostat is the advice for the TR4 to reduce the bypass to 8mm or 8.5 mm or plug it completely? JJC

[Hamish]

1 hour ago, JJC said:

Thanks for the posts. There is a YouTube video showing the bypass blocked completely (WEGS Garage, TR4 overheating). But I take it from Marko that some flow is required. So with a non bellows thermostat is the advice for the TR4 to reduce the bypass to 8mm or 8.5 mm or plug it completely? JJC

There is some info on this site
well worth searching  for Eg

just don’t make my mistake 

Edited June 19, 2020 by Hamish
Sp.

[Z320]

Hi,

I checked both and for any reason (don't ask be why)

the resistor down to 8.5 mm on the pump housing seem to be

some more effective than on the thermostat housing or in the hose.

But stay calm about that.

Ciao, Marco  

 

[JJC]

Hamish, Marco, many thanks. I even managed to get the “search” to find Hamish’s post. It just proves “if anything can go wrong it will”. The pictures are great.

I like the look of the 22 mm plumbing cap so plan to go that route. Nothing in my box of come in handys bet they come in bags of 10. JJC

[Z320]

Please first look at your water pump housing,

if you own a 4A the bypass should already be reduced to 8.5 mm.

If not put a 8.5 mm drilled "anything" in the bypass hose.

But this is nothing about your problems.

 

Edited June 19, 2020 by Z320

[Andy Moltu]

Shoving a bit of hose inside the bypass hose does the job.

in many ways the exact bore is academic you need it to allow a little bit of coolant flow to prevent hotspots and air locks but sufficient restriction so that the vast majority of coolant flow goes through the rad when the stat is open. Why Triumph used such a large bore for the bypass hose seems perplexing.

[Z320]

Don't be fixed on the bypass,

this was not your problem before the Fo8 repair and is also now not your problem

[BlueTR3A-5EKT]

2 hours ago, Z320 said:

Don't be fixed on the bypass,

this was not your problem before the Fo8 repair and is also now not your problem

We have deviated from the original issue of the original first post. 

Peter W

[JJC]

Wait and see. Road test some time this week will then let you know whether or not the mod works. Made by an expert friend. “Only took minutes “ he said. JJC

[JJC]

The good news is that the beautifully engineered mod by RVWP worked and it no longer overheats. The not so good news is that he lost sight of me on the road test because of black smoke and flames (with the odd explosion). But he found me when it expired and towed me home. My other expert friend fixed the Strombergs now all looks good for final proving test. JJC