TR2/3/3A Overheating TR3 - a few questions

[TR3driver]

Because it still heats up at stoplights, I'm wondering if maybe I should restrict water flow through the bypass like I've seen some of you do with the 3/4" pipe cap with a hole drilled in it. Thoughts? Will this help more?

On my 3A, it didn't seem to make much difference; either when I was having serious overheating problems or after I got them solved (by having the radiator recored with a modern Modine core).

But on the TR3 with a stock-style radiator it did seem to make a noticeable difference. I'm guessing it depends on how much resistance to flow the radiator presents at idle rpm.

BTW, I used a 3/16" hole in the bypass restriction, plus a 3/16" hole in the thermostat to ensure there was still enough circulation with the thermostat closed. Might not be necessary, but I felt safer that way.

Another alternative is to buy one of the reproduction 'sleeved' thermostats. These work like the original thermostat, with a sleeve that moves to restrict flow through the bypass once the thermostat is fully open. But the thermostat used is a modern "wax pellet" design, so doesn't suffer the flaws of the original "aneroid" type.

Used to be you had to buy these from one of the Jaguar sites, but I think Moss carries them now (still at a Jaguar price, though

)

 

[Geo Hahn]

I blocked my bypass hose using a 3/4" copper cap with a 3/16" hole drilled in it:

No idea if it helps -- given where I live & drive I try almost everything that someone says helps the TR stay cool.

There is a difference between getting hotter (e.g. at stop lights) and overheating. Time will tell you which is which.

 

[Ken_McGuire]

That is the picture I have seen before. How do you keep the pipe cap from heading on down the bypass hose. Does it just stay in place even under pressure?

 

[bgbassplyr]

Hose is curved, pressure is equal on both sides of the pipe cap.

 

[Geo Hahn]

It is a snug enough fit that it isn't going anywhere. Even if it did move it couldn't get away as it would be stopped by lower connection.

Think about it -- the pressure w/i the cooling system has no effect on that piece, only pressure per se is the force of the coolant being moved by the water pump which isn't exactly a fire hose.

 

[luke44]

I can't claim a lot of expertise here being as my car is not on the road yet, but I can tell you what I have read in my research with various history books like Piggot etc.

The TR3A, with the wider opening, had cooling problems the small mouth TR2 or TR3 never experienced. According to the records, a radiator duct was added shortly after the problems started to be reported and apparently it was also offered as a no charge add on for any customer who complained about overheating. Nothing fancy, but seemed to do something. Moss part #855-125. https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29121#top. I'm definitely putting it on my car.

 

[TR3driver]

Another point not mentioned in the catalogs; the factory modified the 3A grille to have wider openings for more airflow. Apparently some reproduction grilles still have the narrower openings.

https://www.tjwakeman.net/TR/FAQ_grill.html

 

[Member 10617]

Ken,

I'm sorry that I cannot answer your question because the people at the shop who installed the radiator figured out the problem. The thermostat was not working properly (it was sticking closed, car was overheating) so they installed a new one.

As for the radiator cap, when they installed the radiator, they put on a cap that normally fits a regular TR3 radiator. But it turns out it extended too far into the neck of the radiator and did not allow the spring to move. The problem was that pressure built up and a hose blew. They discovered that the new aluminum radiator takes another kind of cap. When I asked them if I needed to buy an extra one for backup, since it was a special cap for this radiator, they said no, that you can buy one in any auto store.

Can't be more specific, but just be sure that the cap fits properly on the aluminum radiator.

BTW. Along with the new radiator and thermostat, I had a new water pump installed, the old 4-blade fan removed and replaced with a more efficient plastic fan, and a new electric fan installed. Never runs hot now.

Now here's a frightening thought: On a radiator website I found, I read this: "The average service of an OEM copper/brass radiator is six to 10 years, and eight to 12 for aluminum. That's hard to believe, but then we are talking about "averages." Nevertheless, that's not a long time.

Because the chemicals in antifreeze break down over time, I am told that to get the most longevity out of a radiator, you have to be sure to change your antifreeze every three years, and I assume that also means a thorough drain and flush.
Another mechanic who has installed many of these TR3 aluminum radiators said that I should flush the aluminum radiator annually or at least every two years to make them last a long time. The problem with the aluminum radiators has something to do with chemistry -- not my best subject in college.

 

[Ken_McGuire]

Thanks, Ed. I haven't solved the problem yet. I have a new sleeved thermostat on order - should be here by the weekend. I've also ordered some water wetter, and I'll probably also restrict the bypass. I really would like to keep the stock fan in there, but if I can't get enough cooling with the rest of this, I'll consider changing it out.

Appreciate all the help. This is my first Triumph and I'm having a blast both driving it and working on it. Always something to do...

Ken

 

[Member 10617]

Ken,

You're right about that: "Always something to do." But the payoff is great with these fabulous cars!

 

[Twosheds]

Thanks, Ed. I haven't solved the problem yet. I have a new sleeved thermostat on order - should be here by the weekend. I've also ordered some water wetter, and I'll probably also restrict the bypass. Ken

If you use the sleeved thermostat, you don't need to restrict the bypass. The sleeve blocks the bypass.

 

[TFR]

I just did a bunch or repairs on my TR3 engine to help prevent it from over heating.
For some reason my head gasket was pushed into the #4 cylinder from over heating. After I had the head milled and a new gasket installed it still ran fairly hot. I noticed the water level slowing lowering. It was running out of the overflow tube. So I added a catch can. This helped but the temp still ran over 185. I used a Hayden fan on the radiator.
Now I have to admit my engine was never boiled out when being rebuilt. So I'm sure there is a lot of crude floating around. I also removed the stock fan when I installed rack and pinion steering. (I didn't have to, there was room for it). I thought the electric fan was more efficient so I didn't need the stock four blade monster.
To help my problem...
First: Use the correct thermostat. One that blocks the bypass until the engine temp cases the thermostat to open allowing the water to flow.
Two: I installed a catch can to help retain the hot water when it is forced out by the hot engine.
Three: Installed a 15 blade TR6 fan and mount on the fan nose.

Now no matter how hot it is outside and I am stuck in traffic the engine stays below 185.
By the way I can explkain how to make a 15 blade fan work in the TR3 if anyone is interested and also I have an 8 blade TR6 fan for sale.

 

[Ken_McGuire]

OK, pulled the thermostat this evening, and it is the cheapo, un-sleeved version, and there is no plug in the bypass. So I think I know exactly what is happening now. When the temp hits 185, the (unsleeved) thermostat opens and I get a bit of cooling from the coolant which has been sitting patiently in the radiator. However, the temp won't stay there because it is not forced back through the radiator - rather it just continues flowing through the bypass (with a little probably going through the radiator).

I have the correct, sleeved version arriving tomorrow from Moss, so I'll put it in tomorrow evening, refill the coolant, and take it for a test. I also bought some water wetter that I will add when I refill with coolant. Hopefully, this will make a big difference.

Thanks for all the suggestions.

Anybody know how to loosen a stuck stopcock? I wound up draining most of my coolant through the rear engine block stopcock because the one at the bottom of the radiator is stuck. I am afraid to try to hard to turn it for fear of breaking it off!

Ken

 

[TR3driver]

Anybody know how to loosen a stuck stopcock?

Only by removing it from the car, and disassembling it. There is only a cotter pin holding the whole thing together; remove the pin plus the washer and spring that should be under it, then tap the tapered plug out of the body.

Clean it up, use some fine abrasive to lap the plug to match the body, then reassemble. Chances are you'll want to replace the spring, washer & cotter pin.

PS, Oh yeah, I think there is also a funny shaped washer under the spring.

PPS, my radiator shop just stuck one of these in

and it seems to work fine. If the originality bug bites me again, I might put the original back, but for now it ain't broke so I'm not going to fix it!

 

[Ken_McGuire]

Thanks, Randall. Think I'll leave it for now - like you said, if it ain't broke, don't fix it. Coolant was super clean and flowed very well out of the block. I'm not planning to create any more problems!

Ken