TR2/3/3A Any thoughts on TR3A overheating struggle?

[TR4nut]

Thought I'd tap the collective wisdom here one more time. I've been working through the 3A I recently acquired - car sat for about 4-5 years until my purchase. After I got it restarted from its slumber my fight turned to the overheating problem and I'm still fighting it.

Here's what I've done so far:

Replaced radiator with an unholed one - good improvement
Changed out waterpump/thermostat.
Checked and slightly adjusted capillary gauge to read 212 in a pot of boiling water.
Tested radiator for exhaust gases - came back negative.

We are starting to get cool weather in Texas - on Saturday I took it out for a long jaunt, maybe in 80 degree weather roughly. You could see the car get to operating temp nicely and see when the thermostat opened. Over the course of about a 1 hour drive, with a breakfast break in between, the car very slowly increased temp to near 212 - even with the heater on. I reran it in the garage without the heater on, but blowing from a shop fan into the radiator, and I still climb to 212+. It does not seem to ever stabilize to a running temp. This does not seem at all right to me.

The car does not pop or belch fluid on shutdown - but it clearly is hot. I suspect an exhaust manifold leak so will be pulling that anyway. While I'm in there I'm strongly considering pulling the head 'just because'. I do have a spare head and new head gasket I can install and it will give me a chance to look at condition of lifters etc even though that is not an overheating issue.

Any ideas? Wishful thinking on my part? I'm running out of thoughts here.

 

[NutmegCT]

A quick thought: when you flushed the engine, what was the condition of the coolant? Possible crud blocking the flow?

Tom

 

[TR3driver]

Based on recent experience, I question the "unholed" radiator. While fighting similar problems with my TR3, I installed the "recently recored" radiator from the wrecked TR3A. It had been working fine before the car got wrecked, but apparently afterwards the stop-leak I had been using left a coating of gunk on the inside of the tubes that spoiled its efficiency. The radiator shop said it flowed "fine", but then when I eventually insisted that they "rod it out", they found that the passages were too small for the rods!

Might also be worth swapping out the carb jets & needles. Many years ago I worked on a TR3A with similar issues and I believe that was most of its problem. Every time the carbs are assembled, the jets have to be centered to the needles. If they aren't centered quite right, the needles rub against the side of the jets and, eventually, wear. The result is a substantial alteration in the mixture curve, such that when you set the mixture at idle (as recommended), the cruise mixture is way lean. Persistent overheating was the result.

One sign that I should have recognized was that the exhaust manifold also showed signs of overheating. It was a funny color when cold, and eventually I saw it glowing red after an extended freeway run. However, I suspect you could have a less severe version of the same problem without the manifold glowing red.

I believe this may be a common problem with those old SU carbs, as my buddy's MGA had exactly the same issue. His was so bad, though, that the idle mixture could not be set lean enough!

 

[TexasKnucklehead]

Sorry to hear about the trouble. I wish I had enough will power to get up early and meet you at one of those Saturday morning breakfasts.

Saturday afternoon, I got to ride in a recently assembled yellow TR3 after a few club members tuned it up. The temp on it was going from normal running temp to pegged hot -because the electric sending unit wire was shorting to the shield. But after that was fixed, a couple mile ride around a few blocks, the temperature slowly climbed until I was waiting for a boil over. It didn't boil over and the engine has less than a few hours, so I'm hoping it heals itself with a little time on the engine.

I'm not sure what to offer either of you, but I do have a radiator (with the hole) that allows mine to run in the garage without overheating, and you are welcome to borrow it.

Jer

 

[hondo402000]

you might have a radiator issue but if your exhaust manifold is glowing red then I bet your mixture is running lean. One of the things the charge of gas does in the combustion chamber is to cool the cylinders, too lean and you will run hot and the noticable sympton is your exhaust manifold glowing red.

richen up the carbs, SU's I beliver you would adjust the bottom jet nut, lefty is richening again be sure. somebody else can chime in on how many turns, that would be the easiest fix and see if it works, then go for the internals of the engine. wonder if mecuric acid flush would work, if it didnt eat everything else up?

I finally started going by the easiest fix first rule. EFFR
make a list of easiest to difficult fixes for a problem or cheapest to most costly. Always saved me time and money, unless you got to the bottom of your list and it still didnt fix it HA
Keep Driving!
Hondo

 

[JerryVV]

Are you getting air flow thru the radiator? Try making a shroud out of something just to experiment being certain to not allow the air to go around the sides of the radiator instead of thru it. If that helps then fabricate a better shroud. I seem to recall reading about an aftermarket grill not allowing enough air to pass thru but I don't know if that is just rumor or if factually a problem.

 

[Gordon_Dedrick]

Standing over TR3 SU's turning the nut to the left is LEAN, and to the right is RICH, I believe.
Overheating is one of the toughest things to fix. Any chance you rodded out the drain at the back of the block? That's an area that clogs with crud and blocks cooling flow.
Gordon

 

[tinman58]

Check, and recheck your timing! I had the same problem and pulled the head rad. all of that and then come to find I had the timing WAY out of time. It still ran good but HOT!!!!!

 

[TR4nut]

Well, still haven't solved it but I thanks for the good ideas so far, will test them this week. I think the radiator is good as I used it to break-in a newly rebuilt engine on a running frame I use. It was the main reason I used it - I think it is a tested quantity. It did help a lot, but the problem is not gone.

Block is very clean - this is an older restoration, but with minimal time on the engine, probably less than 1000 miles. Coolant was super clean and the block drain flows freely.

Carbs were completely gummed up, could not get jets to budge so I rebuilt using Joe Curto's kits. New jets and needles, everything centered. I'm running about 12 flats down, just checked with a color tune and #1 looks a little rich, and #4 might be a little lean still.

I did advance the engine quite a bit, but nothing out of line compared to my TR4. It was set way retarded when I picked up the car, and you could feel it bog down with zero power. Initially it was 0 degrees advance at about 1200 rpm, now I'm about 6-8 degrees at idle and about 22 degrees all in at around 3000 rpm. No pinging, but I may back off a bit and see if I can keep the power but get it a little cooler.

Ps. Forgot to add - yes have ducting in place for the radiator.

I'm going to go ahead and change out the manifold gaskets, need to get access to the starter motor anyway and want to replace the exhaust manifold with a prettied up one. About a month away from VTR nationals, and if I have to I'm going to trailer it there!

 

[Roys]

22° is not enough - too retarded causes overheating-especially shows up as a red exhaust manifold(gas still burning out the exhaust) . I run 30-32°max , no vac line hooked up

 

[angelfj1]

Well, still haven't solved it but I thanks for the good ideas so far, will test them this week. I think the radiator is good as I used it to break-in a newly rebuilt engine on a running frame I use. It was the main reason I used it - I think it is a tested quantity. It did help a lot, but the problem is not gone.

Block is very clean - this is an older restoration, but with minimal time on the engine, probably less than 1000 miles. Coolant was super clean and the block drain flows freely.

Carbs were completely gummed up, could not get jets to budge so I rebuilt using Joe Curto's kits. New jets and needles, everything centered. I'm running about 12 flats down, just checked with a color tune and #1 looks a little rich, and #4 might be a little lean still.

I did advance the engine quite a bit, but nothing out of line compared to my TR4. It was set way retarded when I picked up the car, and you could feel it bog down with zero power. Initially it was 0 degrees advance at about 1200 rpm, now I'm about 6-8 degrees at idle and about 22 degrees all in at around 3000 rpm. No pinging, but I may back off a bit and see if I can keep the power but get it a little cooler.

Ps. Forgot to add - yes have ducting in place for the radiator.

I'm going to go ahead and change out the manifold gaskets, need to get access to the starter motor anyway and want to replace the exhaust manifold with a prettied up one. About a month away from VTR nationals, and if I have to I'm going to trailer it there!

Randy: I thought I would offer some data for comparison. The Grey Lady has a "new" engine, that is it truly only has maybe 900 real miles. So, all of the passages that hold coolant are squeaky clean, the carbs have been maxed out (via color-tune), timing at spec and she will idle all day ay 185 F all day.
Getting back to the radiator. it's an original with hole but was refurbished by a rad shop including rodding. I run a 7psi cap. The coolant is a Prestone mix with water wetter. For comparison, the temperature differential across the radiator averages 9 degrees F at idle(1050 rpm) stock fan. Temps were measured with a handheld infrared gun So, in order to eliminate the radiator take some readings and compare to mine.

Good luck

Frank

 

[JerryVV]

Sounds simple but check to see if you have the correct cap. I believe that you need a cap that will seal at 1". Some Tr's have a deeper filler neck and have had newer replacement caps installed. Looking for possible causes.

 

[Geo Hahn]

...For comparison, the temperature differential across the radiator averages 9 degrees F at idle(1050 rpm) stock fan. Temps were measured with a handheld infrared gun...

FWIW - that difference seemed low so (since I just came in from a drive) I measured mine at hot (185°) idle and got a difference of slightly more than 20° top tank v bottom tank.

That is on a recently re-cored stock radiator with a crank hole, but also a blocked bypass hose, well broken-in engine and a tropical fan (the latter two factors possibly accounting for the difference).

 

[Crankshaft]

I have seen the term tropical fan used in this forum before, that I am unaware of exactly what this fan is, and where they might be available. As you might guess from this, I also face some overheating problems from time to time. (60 TR3A)

Crankshaft

 

[TR3driver]

FWIW - that difference seemed low

This seems backwards, but the temperature difference will actually be larger when the thermostat is not fully open (meaning the Tstat is controlling the temperature)!

The Tstat works by blocking the flow into the radiator. At lower flows, the coolant inside the radiator gets cooled farther, which reduces the amount of heat conducted from the coolant to the radiator fins & air.

So really, to get any meaningful comparison, you need to either have the engine slightly overheated (to ensure the Tstat is fully open) or take measurements with the Tstat removed.

 

[Geo Hahn]

I have seen the term tropical fan used in this forum before, that I am unaware of exactly what this fan is...

Here are some images from the web:

As those show, the fan has more blades and much more pitch than the stock fan.

I suppose that pitch robs some HP though I don't seem to miss it.

The tropical fan is not a cure for overheating -- a TR with stock equipment in good nick should not overheat -- but in some conditions it helps keep the engine cooler. I do a lot of slowish mountain driving and occasional stop-n-go traffic in 100+° heat -- in those situations I believe it is especially helpful.

 

[angelfj1]

...For comparison, the temperature differential across the radiator averages 9 degrees F at idle(1050 rpm) stock fan. Temps were measured with a handheld infrared gun...

FWIW - that difference seemed low so (since I just came in from a drive) I measured mine at hot (185°) idle and got a difference of slightly more than 20° top tank v bottom tank.

That is on a recently re-cored stock radiator with a crank hole, but also a blocked bypass hose, well broken-in engine and a tropical fan (the latter two factors possibly accounting for the difference).

Ah, yes, my mistake. I went back and 9 degrees was the lowest ave. differential and 12 degrees was the highest average AND the temps were Centigrade. Since each Centigrade degree is 80 percent larger than a Fahrenheit degree. So, the 9 degree C differential would be equivalent to 16.2 degree F differential and the 12 degree C diff would be equivalent to 21.6 F. Similar to what Geo. recorded.

 

[TR4nut]

I haven't had too much time to play today so don't have a temperature profile yet on the radiator. But I'm still skeptical it is the issue given previous success with it.

Forgot to mention, have a tropical fan on this one also, so that isn't an issue.

I did recheck timing, I was running about 25 degrees advance at 3000 rpm, I've bumped it up a bit to 31, which is about 12 degrees at 1200 rpm. No pinging noticeable at this time, will be checking carburetion again too.

 

[tdskip]

Keep us posted Randy.

 

[TR4nut]

Give Roys and tinman a cigar, I think they pegged the main issue - car is running much better now advanced as it is. When I picked up the car it was so far retarded that performance was horrible, I set it up pretty closely to my TR4 which does not run with that much advance - pinging occurs otherwise. For this car, going to over 30 degrees at 3000 rpm is no problem at all. Peppier and seems pretty well behaved so far. Still gets slightly higher than 185 but I think this time it is stabilizing. Thanks!