TR2/3/3A overheating tr-3

[captainde]

I finally gto the tr-3 running however the engine is running hot, the prior owner had the rad recored and the crank hole removed and said it ran cool, the car sat for 12 years and I backflushed the system which did not help, I then removed the thermastat and boiled it to see if it opened, it did, but right around 100 C, I took out the thermastat and filled the system with water, when I run the engine it will run at a little over 70 c until I increase RPMs then it will go over to 100C, I put a thermometer in the filler neck and the temp read 80C, so far that is all I have done to the cooling system. Does anyone have any ideas?

Thanks,
captainde

 

[tdskip]

What came out when you back flushed the system? I'm thinking that the block might be gunked up.... (sorry).

Do you know that your temp gauge is accurate?

 

[captainde]

there was just some gunk in the thermo housing and I had to poke the block drain with an ice pick to get the water flowing, but it was flowing pretty good, as for the temp gauge I'm not sure wether I have another one to switch out, or maybe it's the sender. I may be able to borrow an IR temp reader from a friend of mine to check the block temp at various places. Should I put the thermostat back in the car?

 

[tdskip]

Having to pick at the block drain suggests an accumulation of gunk in the system, it might be localized to the drain but....

If the thermostat is working OK then I'd reinstall it. Might be worth aggressively flushing the block again and/or using a flushing solution per the directions.

I'd also suggest that you wait to see what other offer up here before trying to swap out gauges and senders since chances are they are probably working OK and the car is in fact getting hot.

Hang in there!

 

[TR3driver]

Just some food for thought : when I bought my TR3 it came with a radiator that had been recored not long before it was parked 30 years ago. I had it rodded out "just in case" and they said it was about 30% blocked. I replaced the thermostat housing with the housing & thermostat from my wrecked TR3A and backflushed the block with the garden hose. No trouble with overheating either idling for long times or on short trips around the block; but on the very first first longer trip it kept getting hotter and hotter then finally boiled over about 30 miles from home.

Apparently there had been lots of crud stuck inside the block, that the backflushing with the hose failed to dislodge; but it came loose with the heat and vibration of a longer trip. When I used water combined with 100 psi air to backflush the radiator, I got lots of big chunks out of the top of the radiator.

I also blocked off the thermostat bypass (since I use a modern thermostat instead of the original, which had a sleeve to block the bypass when it opened) and drilled a 3/16" hole in the thermostat backing plate so some water could circulate even with the thermostat closed. Now it runs almost too cool!

 

[captainde]

Thanks for your suggestions, I will buy a flush kit and reinstall the thermastat. Does everyone with a new style thermastat block off the bypass and drill a hole in the backing plate ogf the new thermastat? I may consider doing that too.

thanks,
captainde

 

[Geo Hahn]

Not everyone, but some or perhaps many. I used a 3/4" copper pipe cap with a 3/16" hole in it to allow some flow (though for many years I just had a piece of broomstick jammed in there -- not elegant but also worked).

 

[Adrio]

I too am wondering if the block may be gunked up. When I rebuilt my engine in the TR4 the block had a lot of stuff in it. I had to go through a lot of effort to get it out, but that is because the engine had been idle and dry of coolant for near 30 years (I had filled the rest of the engine with oil all that time ago so the rebuild was a piece of cake). I suspect your may not be as hard to clear out since it has remained "wet".

 

[Geo Hahn]

I found a lot of gunk around #4 when I had the head off. Rigged up a 'liposuction' by connecting a long thin brass tube to my shop vac and probing and sucking the stuff out. Not really gunky, more like sand.

 

[captainde]

I bought some engine flush and ran the engine at idle for a time as the temp gauge climbed to between 70 and 100C, as I increased rpms , the temp went higher to 100C, when I decreased rpms the temp came down to between 70 and 100C again, eventually the temp went back to 100C at idle. What I'm wondering if I have an air lock in the lower hose that runs from the radiator to the water pump causing the pump not to push the proper volume of water through to the front of the block. Any thoughts on that?
Thanks,
Captainde

 

[jessebogan]

For proper cooling and circulation it really needs to have a thermostat. Try to find one that opens at around 160F. The sooner coolant starts flowing through the rad, the better. Next, use coolant, not just plain water. Make sure the pressure cap is working also. The pressure increases the boiling point 3 degress with every increase in PSI. If the car is running hot at idle, I would look at the radiator first. Unless your ambient temps are really high, it should be able to shed the engine heat OK, as long as all of the cooling system works. If you need to (and if it is really kludged up you might want to), you can remove some of the core plugs (freeze plugs) to gain access to the inside of the block A long thin screwdriver and tools amde from coathangers can help here, and you can pour water in from the thermo housing to help flush it out.

Good Luck

 

[Geo Hahn]

I've had a few cars that were the dickens to chase the air out of the cooling system -- burping radiators, massaging hose, sacrificing goats, etc. but never had a problem with the TRs.

Looking back at your original post:

...when I run the engine it will run at a little over 70 c until I increase RPMs then it will go over to 100C, I put a thermometer in the filler neck and the temp read 80C...

Are you saying that when the gauge reads 100C the coolant in the top of the radiator is 80C? 80C is about 176F -- not even up to operating temperature.

Could be worth your while to but or borrow an infared thermometer (Harbor Freight has em cheap) and see what the temp really is at the tstat housing (where the sender is).

In any case, these engines do get hot if the sit an idle on a warm day.

 

[captainde]

Hi Yoda,

I bought the IR thermometer from harbor and checked the thermastat housing, head and rad temps, they were all around 75 to 80C when the temp gauge was reading 100C. Also I did not put the thermastat in but I did put the 3/4 pipe cap with the 3/16 hole drilled in it, I inserted it in the bypass hose. I will buy a thermastat and put that in as well as a tr-4 rad cap. I thin the temp gauge may not be fully immersed in cooling fluid and maybe that is why it's reading so high or the sensor has no resistence when it gets hot. Anyway at least I know what the temp is now. Also, there is a 4 lb rad cap on there now and it never seems to pressurize the system, maybe it is no good as well?
Thanks for your help with the 3/4 pipe cap idea.
captainde

 

[TR3driver]

or the sensor has no resistence when it gets hot.

The original temp gauge on a TR3 is mechanical. If you have an electric one, it may be a TR4 unit (early TR4 gauges look very similar except for being electric instead of mechanical). If so, it needs a "voltage stabilizer" in the circuit, otherwise it will always read high.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Also, there is a 4 lb rad cap on there now and it never seems to pressurize the system, maybe it is no good as well?[/QUOTE]The stock radiator takes a special cap, not available in regular parts stores. However, many of them have a listing that is wrong, so it's possible someone has installed the wrong 4 psi cap.
Or it may simply be bad.

-- A different Yoda

 

[Adrio]

I think Randall hit the nail on the head with the voltage stabalizer. I had the exact same problem with my TR3 and that was the issue. Once I built a voltage regulator all was well. If you search through my old posts there should be one with a table of resistance versus temperature from when I took the sender unit and ran a little experiment to give me the characteristics of the unit. I used that to determine the voltage I needed to built the regulator to in order to get the correct reading on the guage.

Also, if I recall, the TR4 electric guage has slightly different numbers on it then the TR3 mechanical guage. I am not at home so I can't tell you the difference, but perhaps someone else can. Otherwise I will look tonight and let you know.

 

[PeterK]

Don't believe that the TR3 uses a voltage stabilizer. Came later on TR4s with non-mechanical temp gauge for temp and fuel senders.

 

[TR3driver]

That was my point, Peter, if it has a TR4 gauge then it needs a VS for the gauge.

The stock TR3 gauge is totally mechanical, no place to connect a VS if you wanted to.

 

[Geo Hahn]

And since he keeps talking about 80C and 100C and lives in New Jersey (versus, say, Old Jersey) it seems likely he has a TR4 gauge since it reads in Celsius.

Only took me 3 days and a couple of hints to work that out.

 

[PeterK]

That was my point, Peter, if it has a TR4 gauge then it needs a VS for the gauge.

The stock TR3 gauge is totally mechanical, no place to connect a VS if you wanted to.

Oops, sorry, Randall, I was replying to Adrio saying his TR3 had a VS.

 

[Adrio]

That was my point, Peter, if it has a TR4 gauge then it needs a VS for the gauge.

The stock TR3 gauge is totally mechanical, no place to connect a VS if you wanted to.

Oops, sorry, Randall, I was replying to Adrio saying his TR3 had a VS.

Sorry about the confusion. My TR3 has an electric early TR4 gauge. It looks almost like the real thing only the temperature values on it are 185 in the middle and 250 at the top, I can't see the lowest one since the needle is hiding it.

My point was it sounded like he may have had an electric gauge (even though he had a TR3) as was the case in my car.

I think my poor writing may have made this confusing when it was not before I chimed in.