Rebuilt engine overheating

[John McCormack]

A long post I'm sorry, a bit of explaining to do. I am doing a complete ground up rebuild on a long door TR2 to its original specs, albeit with a better finish than the factory achieved.

 

The previous owner bought the car in 1966, he was the 2nd owner, and started a rebuild but got sidetracked. The restoration was recommenced about 8 years ago and then he got ill and finally realised the car needed to go to someone else to rebuild it. The car has 70,000 miles from new. He had done most of the body rust, panel alignment and many other jobs. He had the engine fully rebuilt by a professional shop. I have spoken to the rebuilder a few times and confirmed the quality of the engine work. The engine is tight with extremely good compression.. Oil pressure is 70-80 psi.

 

The chassis is now complete and we have been running the engine in the chassis to test for leaks and any major issues prior to the body going back on.

 

Last week the engine ran hot and after about 10-15 minutes I shut it down. It boiled post shutdown.

 

I have an original 4 blade fan on the engine and had a normal house fan assisting. It wasn't an overly hot day and it was in the garage with roller doors open at each end for air flow through.

 

I wasn't sure why it had got hot. The engine was acid dipped for a couple of weeks in the rebuild and the engine inside the water pump is clean as a whistle. It has a new radiator without a crank hole and the thermostat (an original sleeve type) has been tested, opens at 145-150 and fully open about 170-175. The timing is 8 degrees advanced at idle, mixtures are fairly rich.

 

I suspected the water pump which is the original but doesn't leak and no bearing noise. The impeller clearance on the back of the housing was roughly between 20-35 thou, with out a gasket.

 

I measured the gasket the pevious owner had put on it at 35 thou thick. In addition what I thought was a thin coat of paint on the pump housing mating surface turned out to be layers of paint and very thick.

 

I cleaned the surfaces back to metal and installed the pump with a 0.4mm (12 thou) gasket.

 

I ran it yesterday and it didn't get as hot as quickly but it still ran hot, I shut it down when it got to 200 degrees measured by an infra red sensor and the temperature gauge.

 

Some knowledgeable people say it should not run hot like that.

 

Other equally expert enthusiasts say it is normal for a new tight engine run on a bench or in a chassis, with no body on to funnel the air and no solid air flow through the radiator, will overheat. Their advice is get the car running and take it for a drive. If it overheats then do something about it.

 

If it it shouldn't overheat why is it?

 

What do people think?

 

[Lebro]

Newly rebuilt engines will generate more heat than a "used" one, plus as I recall from my early TR days, when I was running standard fan only, if the car was stuck in traffic for any extended period it would overheat & eventually boil.

 

Electric fan cured that particular problem, others have fitted "tropical" mechanical fans.

You will probably find that on the road with lots of forced air cooling it will be fine, & things will improve as the engine loosens up.

 

So "DONT PANIC" !

 

Bob.

[John McCormack]

Here it is, the oil and temperature gauges have been removed for transporting to the body shop.

 

[EdwinTiben]

Running idle theres no air flow to cool the radiator, perhaps thats an extra issue. Do you use a correct skirted thermostat , so the bypass is closed after reaching temperature.

[John McCormack]

Running idle theres no air flow to cool the radiator, perhaps thats an extra issue. Do you use a correct skirted thermostat , so the bypass is closed after reaching temperature.

Yes, it is a skirted thermostat. It had a non skirted one in it so I tested a skirted one and fitted it. I then found the bypass hose has an insert with a small hole so the non skirted one was ok anyway.

Thermostat, radiator and engine all appear to be right. Timing and mixture aren't out enough to make a difference.

It is only the pump that I think could be a problem, if there is any problem. I don't know how much clearance is ok between the impeller and the back of the casing?

[Motorsport Mickey]

As Bob says the car isn't made for the engine running without forward air flow into and through the rad. Triumph fitted radiator shrouds to channel air through the rad, if the car doesn't have these 2 bob bits of cardboard in front of the rad to either side and over the top of the rad the engine will overheat.

Luckily you're in a country noted for it's fresh and cool climate...no wait !

 

I'm only kidding you, you've said the engines tight and of course this plus the points listed above is why the engines overheating, get the biggest household fan you've got plonk it in front of the rad and block off the top and sides of the rad in front to make sure the air goes through it and try it again, it should be markedly better.

PS: I'm not normally keen on running freshly rebuilt engines at tickover or low revs, it doesn't help the freshly renewed components to bed in and puts pressure on surfaces where oil supply is important for too long periods, so don't go over the top here.

 

Mick Richards

[John McCormack]

As Bob says the car isn't made for the engine running without forward air flow into and through the rad. Triumph fitted radiator shrouds to channel air through the rad, if the car doesn't have these 2 bob bits of cardboard in front of the rad to either side and over the top of the rad the engine will overheat.

Luckily you're in a country noted for it's fresh and cool climate...no wait !

 

I'm only kidding you, you've said the engines tight and of course this plus the points listed above is why the engines overheating, get the biggest household fan you've got plonk it in front of the rad and block off the top and sides of the rad in front to make sure the air goes through it and try it again, it should be markedly better.

PS: I'm not normally keen on running freshly rebuilt engines at tickover or low revs, it doesn't help the freshly renewed components to bed in and puts pressure on surfaces where oil supply is important for too long periods, so don't go over the top here.

 

Mick Richards

Thanks Mick. I am also wary of running the engine like this so have varied the revs with occasional blips. It has been run enough now to identify any leaks or major problems so it won't be run again until the car can be driven..Hopefully that will be towards the end of this year.

[EdwinTiben]

Hows the radiator cap ? Is it the correct lbs ? Have had issues myself and other cars from friends overheating because of the wrong modern cap

Edited March 24, 2018 by EdwinTiben

[peejay4A]

+1. A bellows stat will not open properly if you have a radiator cap above 7psi. What have you?

[BrianC]

Are you sure you have no air locks in the coolant? May be worth draining the system, including the heater if you have one, and carefully refilling (slowly) with measured quantities as quoted in the Workshop Manual. Also worth checking the radiator cap as suggested by Edwin.

[John McCormack]

Thank you all for the advice.

The cap is a 7lb cap, same as on my other TR2 for the last 40 years, so it shouldn't be a problem.

The engine is in the chassis with no body so no heater or stray hoses. After running the engine I top up the radiator. So no air locks.

TR2s with original fans do overheat in traffic (It does take 10-15 minutes to get this one to boiling point) and without the body the the air is not being sucked through the radiator so much as just being thrashed around by the fan. Like 3As without the fibreboard funnels into the radiator.

Following the advice on here and a bit more thinking it through I don't think it is an issue. Once I get the body on and can drive it I'll see how it goes.

[vivdownunder]

John, have you taken the radiator cap off to see if the coolant is circulating ?. I've tested a thermostat then found it had caught on build-up in the housing and couldn't open. I have at least 3 x NOS bellows thermos if you need one.

 

When testing an engine minus the TR2 apron to channel air to the radiator, a domestic electric fan in front of the radiator helps.

 

Good to catch up the other day. Car will be a pearler.

 

Viv

[Andy Moltu]

Sounds a bit odd.

Did you measure the temperature of the bottom of the rad? If that's hot too then it's unlikely the problem is lack of water flow. If it's cold then consider pump, stat, radiator and airlocks.

 

The other issue to consider is whether the 4 blade fan is up to it - certainly some early cars struggle to dissipate heat when stuck in traffic after a hard run.

 

It might be the engine is just tight and generating more heat.

 

Any evidence of water in the oil or exhaust gasses in the coolant. The head gaskets can blow if the cylinder liner heights are not set properly or settle if anything initially holds up the liners stopping them sitting firmly on the figure of 8 gaskets. Worth a compression test.

[Don H.]

My engine ran hotternhell after rebuilding by Mark Macy and his crew with fast road cam and 87 mm pistons and liners. Timing at 14-16° BTDC at 1200 rpm on distributor rebuild by Jeff Schlemmer. Originally back on the road with Wizard aluminum radiator, now with re-cored original. Rebuilt with five-vaned "high throughput" water pump. The car would puke coolant in stop and go driving at ambient temperatures above 20º C and was borderline even in cold weather.

I did a lot of stuff working on the cooling. I fitted a six-bladed higher pitch tropical fan (from early-mid sixties six-cylinder Triumphs) and that seemed to make a small difference. Checked timing, mixture, etc. Judged the higher vane water pump to be a waste of time, although never confirmed the impeller-to-housing clearance, which is something still on my list (probably when I put the original four-vaned pump back on.)

Refitted the overflow bottle that was on the car when I got it -- TR4 style fitted in period, apparently. That helped prevent coolant from leaving the system as it resiphons back in on cooling. A useful mod then and now I'd say.

Tried Water Wetter -- one of those foo-foo juices that, to my surprise, really did seem to help a bit.

Best thing I did was run the living daylights out of the engine for several thousand miles, in the goal of properly bedding in everything of course. The engine does indeed run cooler now. I expect it do run cooler still with a few more thousand on the clock.

The tropical fan got bent in a slipped trolley jack incident, and when it goes back together it's going to have one of Macy's modern high-flow fans. Mark swears they'll give enough airflow to cool any TR. We'll see...

I'll also make sure the paperboard ducting is sealed tighter to the radiator when the car goes back on the road. There was a half inch or more clearance on both sides where one could imagine air that would otherwise be rammed through the radiator could spill over the sides, and I want that airflow doing heat exchange.

[John McCormack]

Thanks again.

It has a new stock radiator, no crank hole. The radiator is brand new and flowing well.

The timing is at 9 deg BTDC.

Mixtures are bit rich.

Water pump is working normally with about 40 thou space to back of housing with gasket and sealant.

I have used two thermostats. The first one was a Brydon with a plug in the bypass hose with a small hole to allow a little flow with the thermostat closed. This thermostat started opening at 165 deg F, fully open at 175 . The 2nd skirted one starts opening at 155 and fully open at 165 so I fitted it.

There is no body so no funneling of air through the radiator. While you can feel air is going through the radiator most of the air is just being thrashed around behind the radiatior.

The car is being restored to original specs so the fitting of a 6 blade fan or an electric fan, both of which I have, is not an option at this time.

It takes about 15 minutes running at idle with periods at higher revs before it overheats.

I don't now believe it is a problem and only driving the car will tell.

The chassis went back to the body shop yesterday so hopefully in a year or so I will have it on the road.

 

It takes about 15 minutes running at idle with periods at higher revs before it overheats.

I don't now believe it is a problem and only driving the car will tell.

[Hamish]

 

The chassis went back to the body shop yesterday so hopefully in a year or so I will have it on the road.

.

How come it takes so long ?

 

On the telly it takes couple weeks tops !!!!

 

H

[TorontoTim]

On the telly it takes couple weeks tops !!!!

 

On the shows I watch, they can do a whole restoration in half an hour.

[irrational]

I would expect overheating in the scenario you describe as there is no airflow really to dissipate the heat.

The fan is not very efficient in idle in any case.

I don't think idling that long is good for the engine though. I'd rather go for a drive to warm up the engine.

 

I use a 4psi cap on my car as this is what it is supposed to have and I have an original radiator with hole.

The car heats up steadily under idling or slow traffic conditions but I have never done this for 15 minutes. Slow moving for 10 maybe and that did cause overheating. The second I could move, the temperature dropped 10 degrees F.

Since I am at altitude with comparitively thinnish air (1400m) in a hot climate (30 deg C in summer), the car is actually very well behaved in my opinion. I added a tropical fan I had for usability and now it is definitely better, taking much longer to overheat if at all.

 

Dirk

[Don H.]

Agreed, Dirk -- I run a 4 lb/in² cap too. What's your logic in running a 7 lb/in² cap in an otherwise very, very original restoration, John?

[DaveR]

It could be that the water ways and or the rad have become clogged up with gunge. Not uncommon after a rebuilt. Try flushing out the cooling system.

 

Dave

[boxofbits]

I personally don't think it should overheat despite the body not being in position.

 

When I was at day release technical college in the early '70's the workshop had about 3 Morris Oxford 'B' series engines, a couple of 1500 Ford Pre-Crossflows and 'A' Series Mini engines all running and mounted in welded steel frames for us to work on. I don't remember any of these overheating because they weren't actually mounted in cars.

 

Are you sure the cylinder head is not cracked, or problem with the head gasket? If you can get a coolant pressure tester it might be worth running it with one of these attached?

 

Kevin

[Motorsport Mickey]

Kevin,

 

Stand by me, if a freshly built TR engine hasn't even got the 2 bob bit of cardboard cowl in front of it...and sealed as well you can to the rad it's VERY usual for the engine to overheat at low or tickover speeds.

The mechanical fan causes a blockage and the airflow stalls through the rad, I'm almost certain that's the cause of this.

 

Mick Richards

[Don H.]

Mick, to your point, here's what the seal of my paperboard deflector-to-radiator core seal looked like before I took off the apron. I'll figure out some way to seal this up when my car goes back together over the next couple of months.

[Motorsport Mickey]

Don,

 

Yep, pretty common and worse. The self adhesive foam draft excluder used on house doors does a decent job of closing it up and you can normally fiddle it into position without stripping anything down.

 

Mick Richards

[boxofbits]

Kevin,

Stand by me, if a freshly built TR engine hasn't even got the 2 bob bit of cardboard cowl in front of it...and sealed as well you can to the rad it's VERY usual for the engine to overheat at low or tickover speeds.

The mechanical fan causes a blockage and the airflow stalls through the rad, I'm almost certain that's the cause of this.

Mick Richards

Well if you've had experience of that, then it's more than likely and John's better off waiting until it's all properly put back together. It's funny we used to run these old BMC lumps for sometimes 1/2 hour 45 minutes with no issue. I remember my 2.0 litre Pinto Hot Rod would do 25 or 30 laps at up to 8700 rpm on the straights with no issue, but as soon as you stopped waiting to come off it shot almost instantly round to about 120 degrees. No doubt you experienced similar issues in your TR racer?

 

Kevin