• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)

Overheating at high speeds

Share this page

Gasoline!!!your engine wants a little more octane than its getting.If this makes no difference get ready to put in a head gasket, your may be in the early stages of failure.
MD(mad dog)
 
Simon TR4a said:
Wow, only 500 miles on a rebuilt engine and you are doing 70mph- in a Herald?
Maybe you are pushing it a bit hard..
Simon.
Click to expand...

Uhm you might be right, about the 70mph, that was only a small portion of the drive though. Anything less and I will get run down by other drivers around here. That actually was less than WOT. BTW, if I had a different ratio in the differential, it could do a fair bit more at least on level ground. These cars are WAY under geared.

I let up a bit on the gas pedal this morning and it was a somewhat better.
Of course I also did a few other things:

Replaced the thermostat, it worked perfectly well (tested in a cup of hot water) but it was French. I put in a lower temp unit, but once the engine is hot it shouldn't make a difference. Maybe my LBC just doesn't like French parts.

Took apart the water pump. No damage inside, but there is a big gap between the rotor and the housing. I also noticed that the gasket was very thick ~0.8mm. I took out the gasket and sealed it with permatex. This brings the rotor to ~1.2mm from the housing. I think that this might still be a bit to loose, however there there is a good flow of water in the radiator when I rev the engine.

Cleaned the cooling system with "Gunk" radiator cleaner. Basically just TSP and I doubt it made any difference.

Replaced the lower rad hose with a proper Triumph bit. Instead of one I cut to fit from a longer hose. This shouldn't make any difference since the hose was in good shape, but I had it and everything was all apart.

Now, other than continuing to let it break in, I may well be at the limit of the radiators cooling ability. These cars always had a bad reputation around here in high temperatures. The best solution may well be a big Al radiator. Looking through the Summit catalog, it seems that a standard Chevy rad would be very easy to fit, (space requirements, inlet / outlet location) and they are quite reasonably priced at least relative to a custom rad.
 
70herald said:
Simon TR4a said:
Wow, only 500 miles on a rebuilt engine and you are doing 70mph- in a Herald?
Maybe you are pushing it a bit hard..
Simon.
Click to expand...

Uhm you might be right, about the 70mph, that was only a small portion of the drive though. Anything less and I will get run down by other drivers around here. That actually was less than WOT. BTW, if I had a different ratio in the differential, it could do a fair bit more at least on level ground. These cars are WAY under geared.
Click to expand...

Please induldge my curiosity. At 70 mph don't you run out of country very quickly?
grin.gif
 
angelfj said:
Please induldge my curiosity. At 70 mph don't you run out of country very quickly?
grin.gif
Click to expand...
Depends which direction. Heading west, I would need pontoons in under 45 minutes. North / South I can go somewhat further, and there is a fairly new main road heading N/S where 70mph is the limit, however speeds are closer to 85-90mph.
 
Back
Top