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MG MGB Technical - Running Hot

Just completed restoration of a '78B. Now has an 18Vxxx type refurbished (Marina) engine and Weber carb set-up. Radiator had been very recently recored by PO.
Have noticed at each outing the engine temp. was getting hotter even though both Fans have been switching on OK. The high temp. had me concerned and I feared the hi-heat could damage the Head. (I am a first-time MGB owner and worry alot !!)
Looking for a solution I have just tried adding Water Wetter to a fresh fill of 95% water and 5% coolant.
Now the problem is even worse !!! I drive for about 5 miles and engine temp. goes right up to near the "red" zone, but not beyond... the fans kick-in (even when driving at 40MPH)but don't manage to cool enough to bring the temp. needle even near what I had when the rad. was 50/50 antifreeze. What have I uncovered ? Should I go back to 50/50 and look at another solution. How do I get that engine temp. gauge reading in the middle (safe zone)? This baby isn't leaving the the driveway until this gets fixed right. Suggestions please. Richard
richard

Some possibilities are, in what I am guessing are most to
least likely.

Stuck thermostat (check by starting from cold. The top hose
should start to get hot when the temp reads mid-scale.)

Timing too retarded (is the distributor advance working?)
If your distributor has vacuum advance, are you getting
it from the right place (i.e. manifold or carb depending on
type of dist.)
If no vacuum advance, maybe that's the problem also.
Since the engine was rebuilt, maybe your advance curve is
totally wrong for the combination of new cam, compression,
and anything else changed. If timing is too advanced, you
would have pinging with the overheating. For some reason
I think timing is the problem here, given the combination of
non-stock carburetion and recent rebuild.

Wrong or defective temperature sender installed. (Try to
calibrate with a known good thermometer.)

Mixture way too lean (I'm ignorant about Webers except
that I know the jets are tricky to select and set up right.)

Bad water pump -- stamped-impeller pumps have a
bad reputation also.

Poor-quality recore, or maybe clogged radiator somehow.

Hopefully some of the Weber and distributor experts on the
BBS will have some advice about setting the mixture and
timing.




Ronald

Shot in the dark- are the fans turning in the right direction?
william fox

Ronald had several good suggestions as to the possible cause of hot running.

I suggest a thorough flushing of the cooling system. I put one of those inexpensive Prestone flush kits in mine. The tee fitting goes in the hose between the cylinder head and the heater core. Hook it up to a garden hose and run the water until it comes out clear. You might be surprised at how much brown sludge will come out first.

Even if the thermostat is working, it may be the wrong spec. There are three common settings, 160 degrees for warm weather climates, 180 degrees for normal climates and 195 degrees for cold climates. In Montreal, in the summer, I would expect 180 degrees to be appropriate. You could try a 160 degree 'stat. This will allow the 'stat to open a little earlier. This will let cooler water from the radiator into the block. If the cooling system is not dissapating the heat, no thermostat will do much good.

Make sure that you are running a proper mix of water/antifreeze. In most places a 50/50 mix is about right. I would guess that 5 percent antifreeze will not provide sufficient lubrication for the water pump or corrosion protection for the iron parts.

There have been a couple of threads lately about radiators, particularly the lousy ones imported from China and sold by Moss and others. The concensus seems to be that re-coring locally is a better choice. However, not all cores are created equal. Some shops only use a three-row core. A four-row core is better. If your PO had a poor re-core done, he may have gotten a cheap three-row core, which can't dissipate the heat properly.
Paul Noble

If the fan stat is in the rad them presumably the stat it opening to some extent, at least, if the fans are coming on. Given that this is a replacement engine and not suddenly started with a previously working setup, I have heard that the wrong water pump will fit but pumps significantly less coolant through the system then the correct item. Check the temps of the top and bottom hoses once the fans come on and have been running a while. If the top is hot and the bottom cool then I would suspect lack of flow is the problem. If both are hot then either the engine is putting out too much or the rad can't get rid of it. If there is bags of hot air being blown out by the fans then I would suspect the engine.
Paul Hunt

Gentlemen:
thanks for the advice. I had been reading the BBS Archives seeking suggestions and recognized some of your names here. Glad to receive your competent comments.
I will start with a checklist based on Ronald's suggestions. The other ideas will also be incorporated in my endeavor to correct the situation.
BTW... yes, the fans are turning the right way. The vacuum advance has a hose going to a small square valve sitting just left of the Clutch Housing Box. I see that no one had anything to say about Water Wetter... so that will not be part of my remedies anymore.
I have booked time with a knowledgeable mechanic to review the Timing and Carb adjustments too.
Would like to hear if anyone knows where I could get more info on the Weber DownDraft Carb. in case I may want to fine tune later in the future. Appreciate your time and interest in helping. Will let you know the outcome. Regards, Richard
Richard

Water wetter would only treat the symptoms, not correct the problem.
william fox

This thread was discussed between 21/08/2002 and 22/08/2002

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