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

[Ken_McGuire]

OK, recently my car has started running HOT. Today it was above 200 and when I stopped for gas, lots of water/anti-freeze blew out of the overflow. It only seems to stay near 185 when I'm moving which leads me to believe that water isn't circulating through the radiator and I'm just getting cooling from air flow while driving So - a few questions.

1. I've read on here about plugging the bypass. I live in Cincinnati - would this be a good troubleshooting tool to see if the problem is in the thermostat?

2. If I want to check (remove) the thermostat, do I need to drain the coolant as stated in the manual? Seems like it should be near the "top" of the system, so I'm not sure how critical draining is. I found the drain plug on the radiator, but the manual mentions one on the block - where is it? Do I need to remove it, too?

3. Any other suggestions?

Thanks,
Ken

 

[Andrew Mace]

Ken, I'd give serious thought to a complete drain / flush / refill before doing anything with the thermostat; you can temporarily refill with just water to see if the flush helps enough. These engines often accumulate all sorts of build-up in the block, and that particular drain tends to be ignored when a "typical" drain / flush / refill is done.

Someone will correct me if I'm wrong, but I think it's about the same place on a TR3 as it is on most other Triumph engines: right side of the block, near the rear and below the manifold (and directly over the starter, I think)!

Best to remove the drain tap completely on the block and make sure water GUSHES out when flushing. You might have to probe with a small screwdriver or stiff wire (coat hanger) to break things loose!

 

[Ken_McGuire]

I found the plug in the manual - you are right, it is near the back. I was looking up front. And yes, it is right over the starter. Nice.

When I flush, should I just flush with water? How? I'm assuming just keep adding water to the radiator as it runs out the drains?

Thanks - newby here.

Ken

 

[Andrew Mace]

That's pretty much what I do...just stick a hose in the filler neck!

I recently, after many years of NOT doing so, tried an off-the-shelf chemical flush (Prestone brand) in my Herald. Jury's out (as it always used to be in my mind) as to whether it does anything at all; it certainly doesn't seem like it did this time.... :frown:

 

[tomgt6]

I have used some chemicals mainly to loosen some stuff up and then do the flush. I think the chemical gets some scale off the walls and such. But the hose in the neck like Andy says is the way to go.

 

[TR3driver]

The chemicals sold today do almost nothing; flush mostly your wallet. There used to be stronger ones available (2 parts, had to neutralize the acid after doing the flush), but they seem to be gone, probably not "green" enough. My experiments with "CLR" (a commercial product for removing Calcium, Lime and Rust around the house) were inconclusive.

My method for flushing is to open both drains, poke the drain on the block until it runs free (it's usually clogged with crud), and remove the thermostat housing. Then I unscrew the plug from the cylinder head (where the heater valve would go if I had a heater in my car) and screw in an adapter that lets me connect a garden hose. Turn on the hose full blast, and then I use an air gun to intermittently blow shop air in through the drain valve on the radiator. Probably wouldn't hurt to blow air in through the block drain as well, but you'll have to do some disassembly to get your arm in there (unless your arms are a lot thinner than mine). This loosened up an incredible amount of rust in my project TR3.

Or the other alternative is to take it to a radiator shop and let them flush it. My shop uses a method similar to the one I described, except they have a fitting to blow mixed air and water through a radiator hose. They said they didn't get much more out, though.

 

[Member 10617]

Same thing happened to me, even though I had recently installed a new aluminum radiator. Turns out (1) the thermostat was defective, (2) the wrong radiator cap had been installed. Both were changed, and now the car runs at 180-185.

 

[angelfj1]

Glad to hear you got it sorted out. Going back to basics can work and in this case it saved you a lot of money?

 

[Ken_McGuire]

Hey Ed, how did you find out the thermostat was defective? Did you take it out to check it, or did you just replace it? And what is the "correct" radiator cap. I'm learning a lot and tomorrow looks like it will be a full troubleshooting and perhaps flushing day.

Thanks again,
Ken

 

[JKB1957]

Two suggestions. Try to cover your starter to keep as much of the water off of it as possible. The water probably won't hurt it but it is electrical and British, why court trouble. The second, when you remove the tap from the right side of your engine block be very careful, they can tend to be a little difficult to remove. If you damage the tap you will have to find a new one (easy) that works (difficult). Most of the ones now being sold leak, I know from personnal experience. Check past achives for more stories and how to fix "new" block taps so they don't leak. An alternative is to go to a good plumbing supply store and see if they have a plug with the correct threads for your block. It won't be original, but it will work. If you snap off the tap in the block it's not the end of the world, but lets just say your world will have gotten much more complicated. Oh and use thread paste (plumbing supply store) when you refit the tap to the block to prevent leaks. Good luck.

 

[deadair]

I had overheating problems with my TR3A ever since I completed a ground-up restoration about 24 years ago. 15 years ago, the car overheated again and broke down, so I gave up and left it parked in my garage.

A few months back, I decided to finally get the TR3 back on the road. My first decision was to give up trying to keep everything original and install an electric fan (I also fitted an aluminum radiator, bellows thermostat, six-vane water pump, and aluminum water-pump housing). Now, when the temp gauge starts to creep up to 195, the fan kicks in and brings it back down to 185.

IMHO, an electric fan is a must if you're going to drive a TR3 in today's traffic conditions.

 

[TR3driver]

And what is the "correct" radiator cap.

On most radiators, it is only 3/4" from the top of the neck (where the cap goes) to the lip inside where the pressure relief portion of the cap sits. But on the TR2-early TR4 radiators, that distance is 1". The 1" reach caps are generally only available from a LBC specialist; the corner store may try to sell you a 3/4" cap that will not hold pressure at all.

I actually had my original radiator modified, so I can use a modern 3/4" cap. The cost (as part of other radiator service operations) was minimal, about $15 as I recall.

 

[TR3driver]

An alternative is to go to a good plumbing supply store and see if they have a plug with the correct threads for your block.

An ordinary radiator petcock will also screw in, and work. The threads are not exactly the same, but the tapered threads on the petcock will seal to the straight threads in the block.

 

[Ken_McGuire]

OK, I measured the radiator cap, and it is indeed a 1" cap. Good to go there. Since I have to drain the radiator to remove the thermostat, I may as well flush at the same time, so I'll do that. I figure I'll pull the thermostat and check it in a pan of water tomorrow. I'll bet that is my problem.

Thanks for all the help. I'll keep you posted on what I find.

Ken

 

[TR3driver]

BTW, Ken, if it stays at 185 on the road, then your problem is almost certainly not a stuck thermostat. If the Tstat was staying closed, IMO it would overheat even quicker on the road than at idle (much more heat produced).

But a good backflush (backwards through the radiator) will likely help, and it can't hurt to check the Tstat while you're in there.

My radiator shop wants to replace the Tstat every time, maybe they know something I don't.

 

[Ken_McGuire]

Randall,

I got the same message from someone else, so maybe I'm barking up the wrong tree.

Are you guys all changing your fans? I still have the 4-blade flat metal fan. I think I'll still flush and check the thermostat.

Ken

 

[TR3driver]

After about a year of struggling with the stock fan on the 'project' TR3, I gave up and put the electric fan from the TR3A on it.

Don't recall having nearly as much trouble with the stock fan "back when", but I got tired of fighting with it this time. Removing the front apron is enough of a PITA that I'd like to avoid it for a few years if I can! The 3A radiator had been relatively recently recored and already had the fan on it, so I just swapped in what I knew worked (and it did).

 

[Geo Hahn]

Ken -- Just in case you don't know, you don't want to totally fill the neck of the radiator on the TR3. If you do it will surely puke when it heats up.

I usually fill so I can just see coolant in the bottom of the neck. That big neck is sort of an expansion tank and needs to be almost empty when the engine is cold.

If you had it really full this could in fact be the problem you experienced... not so much a problem as the radiator self-adjusting the coolant level.

 

[Ken_McGuire]

OK, thanks for all the info. After talking with you guys and also some other folks, I am pretty sure I had an airflow problem since it cooled down when I was driving and not sitting still. I still have the old 4-blade metal fan in my car, and it had flat blades. I wound up bending them into more of an airfoil shape by bending the trailing edges away from the radiator. This should dramatically increase air flow through the radiator.

Today, I took it out for a drive and was nervous as the temp rapidly came up. But once it hit 185, it leveled out instantly. It stayed there for most of the drive. It still heats up when I sit (at stop lights, etc.), so I'm not sure this problem is completely solved, but it is definitely better. And I'm nearly positive the thermostat is working as it seemed to instantly stop heating once I got to 185.

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?

Thanks.
Ken

 

[angelfj1]

Ken: From what I have seen and heard from reliable sources, TR engines do not overheat when fresh, that is, when brand new or recently rebuilt (properly). However, in fairly short time scale builds up in the block, cylinder head, and other parts of the cooling system. This scale prevents efficient heat transfer between the engine and the water/coolant mixture. The same thing happens in the radiator. I suspect that a proper flush of the engine and radiator will result in better cooling and lower idle temps.

good luck!