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A contributory factor to overheating


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Hello fellow TR ers

 

Being a very recent member of this forum I haven't read anywhere near all the posts concerning overheating, but there is a contributory factor not mentioned in the last two, but it is alluded to in a round about way by Bob in the last one. Bob said he removed his badges and spotlights. I gleaned the following snippet from an American lady who has a bit of a blog on her TR-ing adventures. I can't remember her name and have not been able to find her web page again, but credit goes to her.

 

She points out that the holes in reproduction front grills are significantly smaller than the original factory grills and says that where at all possible we should keep our old battered aluminium one rather than buy a new shiny straight stainless(?) one. If I remember rightly she states that the smaller holes cause something like a 30% reduction in area through which air can flow through to the radiator. Such a reduction is going to make a big difference. So, if you have knocked out all the other possibilities, or even before you remove the cylinder liners to clean out the rust, and you have a new front grill, it's worth considering.

 

Unfortunately her advice came too late for me as I no longer have my old battered one. I personally never throw anything out but someone else disposed of it on my behalf without my permission. No, it wasn't Mrs B. I haven't as yet had any overheating problems, touch wood, (he says tapping his head) but when you know this and look at the front of the car you realise it doesn't look right and that's why. I have thought about having a go at making a punch and die to enlarge the holes and doing them one at a time in a press. Perhaps when I have ticked everything else off the list.

 

Cheers everyone, Tony

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The competition TR3S cars had a noticeably more open grille, more open than the standard production item let alone the modern (aluminium) reproductions.

i-cMHtmFB.jpg

 

Paul Hogan converted a grille similarly on his TR3S tribute car. He described the technique to do the mod as crimping the grille slats over an appropriate diameter of metal rod, so as not to fold the metal tightly. His grille looks terrific. The original grille is still on my car, but I have a donor in the shop for when I get motivated to make one like the TR3S.

 

I dunno about cooling efficiency (despite what TeriAnn Wakeman says on her site, which is quite a useful reference). They sure look better to my eye, especially compared to the new grilles!

 

i-7TkWRSB.jpg

 

PS: Click on the images for the ridiculously-large original files if you want to study details.

Edited by Don H.
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Well, that's very interesting Don. Thanks for remembering Teriann's name.

You doubt the cooling effect? Surely bigger holes equals more air equals better cooling, especially considering Bob's spotlights and badges were obviously impeding his air flow. Smaller holes, less air flow, reduced cooling effect. It seems logical to me but maybe I'm wrong. It seems like a pretty easy thing to test by swapping grilles on the same car and driving it in similar conditions in a similar manner.

 

Tony

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I'm not debating the theory, I'm questioning the practical application. But I'd love some data -- why not take the grille completely OFF your car and drive around for a while?

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This is from TeriAnn's page:

 

TR3Agrills.jpg

 

The difference is significant. On first glance, I would think that there's a 20 - 25 % difference - and that will influence the total cooling effect. Therefore, Don's suggestion to drive a while without the grill is a good one!

 

Perhaps it's good to start writing (and contributing) a 'sticky' thread here or on the Technicality pages about curing the 4-pot tendency to run hot. I will open a new thread and hope for contributions from others.

 

Menno

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As my grill is a fairly modern thing that doesnt fit that well, with nowt to lose and just for the hell of it, at the start of this season I 'squeezed' the centre of each slat with a pair of grips. Only an anorak would notice from less than 7 yards.

 

That said, even with 7" spots and Kes, the cooling system works fine - even with a hot engine.

 

Biggest and cheapest fix by a clear mile the card shroud and small 10" Kenlow pusher.

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To confirm, my car is an early tr2 with the deeper mouth. What we felt was that the driving lamps and badges whilst reducing the facial area so to speak to direct windflow, moreover the effect was that these things deflected the wind up and over the bonnet. The difference was huge on my car. With a 74 degree thermostat fitted it actually ran too cold on a cool day with the heater on. I have now put the driving lamps only back, this has brought up the temperature by an average 15 degrees. My temperature gauge now sits between the lower intermediate line and the 185 degree marker. For me this is perfect, even in stationery traffic it takes a long time for the electric fan to come on.

With the tr3a's air flow is obviously as critical, not deflecting and not restricting should both be scrutinised.

 

Regards Bob.

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My car had no overheating issues at speed. Only during stop-and-go driving (especially the stop part) did it overheat, coming down as soon as I was able to get moving again. It doesn't seem logical that airflow through different grille styles could be a factor in that case. More likely poor draw due to the ineffective original fan, plus many of the other things noted in the other ongoing thread.

 

It's not impossible that having the duct in place helps direct whatever weak flow generated by the fan through the radiator.

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When I first rebuilt VHP in the early 80's, she overheated terribly.....fine at 65-70mph any faster the temperature would rise very quickly.

 

Contributing factors were

1. The repro grill

2. A rubbish refurbed rad from C and B, (note by Peter W when I took it in for their help as frankly I had run out of ideas.)

3. Running lean at wider throttle openings.

 

I note now that electric fans, are mounted very very close to the rad, perhaps the gap between the standard TR fan and the rad is just too big and therefore pulls air from anywhere of low resistance to flow. That is not through the core.This i think would show very quickly if you don't have the cardboard rad deflectors.

 

Iain

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A roadgoing TR doesn't need an oil cooler. When you instal one to overcome overheating problems, you're looking in the wrong direction.

 

Menno

 

Agreed! An oil cooler does next to nothing for a car in stop and go traffic, where most non-obvious overheating occurs.

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A roadgoing TR doesn't need an oil cooler. When you instal one to overcome overheating problems, you're looking in the wrong direction.

 

Menno

Re-reading Miles' posting it doesn't that he's planning a oil cooler. It was a question... Perhaps I was a little too quick... I only jumped to the conclusion that it would be a shame to spend money on something unneeded!

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I took it as a general addition to your ongoing thread about overheating, Menno. Some of the things not likely to pay off are as useful as suggestions for things that will.

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I took it as a general addition to your ongoing thread about overheating, Menno. Some of the things not likely to pay off are as useful as suggestions for things that will.

You are right. When I needed info on restoring my TR I stumbled upon the same 'oil cooler or not' matter. Luckily, other members told me the same thing we're telling now. It's what you write: helping to find solutions for things that will work!

 

M.

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Thank you for your concern Menno.

 

Actually, my 3A does have an oil cooler, sitting in front of the radiator. Installed by the original restorer who rebuilt the car for fast road going with a hotter cam and Weber 45s. Still haven't worked out whether it has a spin on thermostat for the oil (no evidence of an in-line version). The cooler does obstruct the rad to some extent. so my debate is whether I remove it or not. I will probably adopt Don's 'try it and see' approach at some time (a commodity that is limited in my case!) by removing the oil cooler and see if I notice any difference.

 

Miles

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I have seen them positioned upright, next to the rad on the LH side. That way 80 - 90% of the oil cooler is away from the radiator. Make sure that your protect the cooler with a mesh or other sort of guard. One small stone will jeopardize your trip...

 

M

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Since a few years the TR3A grills are again produced to original specifications, in so far with a larger air inlet surface.

On my 3A I put an opening in the lower valance, same as TR3S. Note that the lower part of the valance covers almost 30% of the radiator

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