MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB GT V8 Factory Originals Technical - V8 operating temperature question

Just got a V8 4.2 litre installed; runs (whether in traffic or at speed) in hot weather (it's 92 deg today) at exactly the 3rd hash mark on the temp gauge -- i.e., halfway between N and H. My other B has a numbered temp gauge, and I believe the V8 is thus running at about 103 degrees C.

That seems too hot. My wife's european car never, ever exceeds 80 degrees F. Do you think this is OK, or do I need to re-think the cooling system? I wonder if putting on an oil cooler would help, but I have no room to do that in any conventional location. Also: I'm using a 13# pressure cap ... is that about right?
Phil

Sounds OK to me - new engines will run hotter anyway whilst they bed in due to increased friction.

My car runs between the N and H sector quite happily and never boils over.

The guages are not that accurate - it might be worth calibrating the temp guage by suspending the sender bulb in a pan of boiling water - then you will know what 100 degees is on the guage.

The rad pressure cap raises the boiling point of water - as far as the engine is concerned the hotter it runs the better for efficiency and wear.
Chris Betson

May be worth checking your timing on a rolling road. I've found it adds an easy 10 to 15 degrees temp when the timing is slightly out (slight enough to cause the rise but not so much that the performance is noticeably poorer).
David.
David

Phil,

I found changing from a 3.5 to 4.6 generated a lot more heat especially in warm weather and traffic jams. A recored rad has partially solved this but I will change to Ali rad later in year. I also use Water Wetter.

Paul
Paul

It would seem to me that if the gauge does not move, regardless of the driving conditions,that the thermostat is doing its job of regulating the temp in the block.

If something was of marginal capacity in the system, when you hit the portion of the operating range where the heat added from the engine outstripped the ability of the radiator to take it away, the temperature of the coolant would go up. If it isn't then it must be being regulated by the thermostat.

Is your gauge working properly? Have you tried changing the thermostat to one with a lower temp?

Waterwetter's benifits are marginal at best and might be good for a few degrees of temperature reduction. The first order effect is the ratio of antifreeze to water, with water having a much better heat transfer capability. I'd run just water with a corrosion inhibitor/lubricant such as those made by Prestone. Of course, this is advise from someone who lives in the desert where it seldom freezes.
Phil

I used to get worried by my MGA reading up to 220F under load with a 7lb cap until I did the calculations: for water at 7lb over atmospheric, you need to be above 20,000 feet for the water to boil at 230F. As Phil says, consistency is what you're looking for, so if you get a steady 103C it's probably nothing to worry about.

On the other hand, your wife's car running at 80F sounds very worrying. As blood heat is 96F that engine must be cool to the touch. FWIW my European car runs at 90C.
dan

Paul
Straying from this thread slightly, was the 3.5 to 4.6 engine swop worth it?
I suspect cooling would be a problem.
My 3.5 will run for ages from cold ticking over stationary on the drive before it gets hot. On the move, the temp gauge sits a fraction below the halfway (normal) position. But once in a traffic jam, which are becoming more frequent these days, it doesn't take too long for the gauge to start climbing.
I think RV8 style headers that exit through the inner wings must be the way to go if the fans are unable to cool the radiator sufficiently.
Al

Guys do not count on seeing your Temp gauge indicating a confortable "N" by using "RV8 style heathers". I also thought they were going to make a visible difference on the gauge the truth is that your car it is going to run with the gauge pointer half way between "N" and "H" my car does despite " ceramic coated RV8 heathers", 22 louvers on hood, 16" puller electric fan, 17" x 18" radiator, water wetter, bla, bla. bla. I think we are just worring too much, my car has never boiled over, but, it is nerve wreking seeing that temp gauge climbing and climbing,
Romney.
Romney

I'm not sure that what's normal for a 4-banger B would be normal for the V8, though we rely on the same gauge as if it spoke the gospel. (Anyone have a Range Rover?; could you look in the owner's manual and see what "normal" op temp is supposed to be?)

A lot of seemingly knowledgable folks have said to me that an aluminum engine should run hotter than an iron engine, in order to develop peak power. Exactly why, I can't remember. Maybe 103 deg C is OK, although I agree that's just a tad warm for most cars ... what's your oil temp? ... I have a vague belief that unless you use synthetic oil, temps over 90C begin to inhibit most motor oils' performance. Someone who knows these things, speak! ... or type!
Ted

On a factory V8 the stat is 82C/180F and the electric fan cut-in is 90C/194F which equates to about mid-way between N and H. The rad cap is 15lb. What does it run at in cooler ambients on the open road? If the open road reading in cool ambients is N but higher in hotter ambients then you would appear to be generating more heat than the cooling system can get rid of, a not uncommon problem. I have seen mine right up at the red when stuck in traffic in ambients of the mid-90s, didn't boil, but it did get a bit lumpy. However those temps do generate a lot of extra pressure in the system.
Paul Hunt

Paul, yes the gauge returns to N at speed in ambient temps of 70F to 75F which is what we are at this time of year, im waiting to see how it does in summer temps. 90F or about, this will be my first summer with those RV8 Htrs. will coment on that later.
Romney.
Romney

This thread was discussed between 18/04/2002 and 20/04/2002

MG MGB GT V8 Factory Originals Technical index

This thread is from the archives. Join the live MG MGB GT V8 Factory Originals Technical BBS now