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MG MGA - Overheating

I have rebuilt an MGA 1500 motor and it continues to overheat. The mechanic told me when he went to install the rings they dropped through and told me at that point that I had a 1600 engine. The stamp on the block is 1500. I know the factory ugraded to a set of pistons for that stock 1600 motor but I curious if that was bored out of a 1500 block to begin with, if anyone knows this history? At this point, my 1500 block is bored out for the 1592 pistons and was additionally bored two thousanths over that in the lastest rebuild. Is this why my motor might be running hot because possibly there is not enough 'meat' between the pistons to dissipate the heat? In a sense I am asking if it sounds to any of you who might be familiar if the motor itself it out of spec at this point and what solutions you might offer to keep it cooler. The running temp is 185-190 and on demand for uphill etc it does run up near boiling. Is there any hope for this motor now that I have just recently rebuilt it? I got it back today...so what to do is my question?

Thanks,
Steve
Stephen Lofaro

I don't know anything about your engine but I can't see why it would mean it ran hot. On the other hand I don't think you have that much of a problem as temps of 185 to 190 are fine. Going up a bit on hills is OK if not too much.

My profile was similar and I fixed everything with a new core in the radiator. Everything else on the cooling side is standard, but I do live in Scotalnd not California! The problem for you is finding a core that works well in MGAs as most modern ones don't. I got mine from Bob West whose cores have a very good name here in UK but I am afraid I don't know where you get something like an original core in the USA.

I wouldn't worry too much even as it is currently running.

Paul
Paul Dean

If it is just rebuilt I would expect it to run a little hotter until it is run in.
d brenchley

Steve

Bear in mind that the company went on to cram 1800cc into that size block. Some guys have managed as much as 2 litres! I have the 1800 in mine and as everyone knows I can hardly get above 170. As Paul says, your temps don't sound that high for your part of the world. Many other factors that will make it run hot are well documented in other threads and in the archives.

Steve
Steve Gyles

Mine is a 1500 bored out to 1600. It runs no hotter than the 1500 which was installed until 2 years ago: 175 on normal journeys, hotter on long or hilly runs.
I must check the radiator at some stage, to see what core it has. Must also install the expansion tank I have had on the shelf for nearly 10 years...
Shane
Shanerj

Agree with all comments above. I would say that the only concern with the engine block, regarding overheating, is if the water passages are blocked for some reason e.g. accumulated rust etc. Otherwise no need to worry about that.

As Paul says, if you do have high running temperatures, look at the radiator core...

Neil MG

The block was acid dipped to make sure that the water passages were clean. The radiator was overhauled...(and I had it taken apart last year and re-sotered all the joints.) I am not sure if it has a modern core or not. So if anyone can advise me how to determine that I will take a closer look to find out. I have heard of some aftermarket aluminum radiators that are higher capacity than the stock radiator, but I have another motor that was out of a Magnette that ran dead nuts on 160 with this radiator. So, after some running in and adjustments I will report back how things are going. I do appreciate the support and comments as it is more encouraging than how I was feeling on the way home...with hot temps and $5000 lighter in my pocket!

Steve
Stephen Lofaro

Steve
There are pictures on Barney's site http://mgaguru.com/mgtech/cooling/cool_100.htm
I believe the original cores are hard to come by these days.
My car would have to get to much higher temperatures than 185-190 before I was worried!
Relax and enjoy it!
Graham V

Hey Steve.

First check your gauge; use an IR thermometer to confirm that it is correct. If it is correct it is either a water flow through the system, or a heat transfer problem with the radiator.

Water flow could be the water pump, or it could be that the block or head still contains scale despite the acid. Rust and other crud can be stubborn and still remain despite acid dipping. I tend to get the block beadblasted inside as well.

I don't think that overboring the block to that extent should significantly impair it's ability to transfer heat to the coolant.

Get a radiator specialist to flow test your rad. They do this with an air blower. They will be able to tell if it is significantly blocked. They may also be able to offer help in backflushing the block or in remedying radiator problems if they are present.

I fitted an aluminium radiator to my car. It's a cheapo Chinese one off Ebay. Cost $200 which was cheaper than having my original one cleaned out, and works very well. My car runs at 160-170F in summer. The climate where I live is very like California; hot.

Fitting an oil cooler is also a good option. I did this on my car as well.
A Bowie

Running across northern France today the gauge sat at 160, not a lot of heat from the heater though.
d brenchley

Steve,

I recently went through this issue after I added A/C to my coupe however my temps were much higher than yours. After doing everything under the sun (new high efficiency radiator core, inner fender louvers, thermostat, thermostat blocking device, etc.) I finally checked the timing. Duh...it was severely retarded (like I felt when I discovered it). Running temperature dropped 10 degrees when reset. It's a quick and easy check to do.

Gene
Gene Gillam

For the last two years, since I put this original motor in my car to replace the 15K926 that was in my car when I bought it back in 1976, both those rebuilds failed terribly with lower end issues, i.e. crankshaft main bearings being trashed. My intention was "restoring the breed" and I felt proud to have an original MGA 1500 block in my car (with the desired mechanical tach).
Now, having this third rebuild from a new mechanic running hot was disappointing. But I can say with firm conviction, it is much better balanced feeling than before and runs smoothly with less than 100 new miles so far. All of the member comments I have received here are quite heartening and we all know with these cars there is nothing more frightening than overheating issues. I do feel with some running in and time getting to and fro I hope to build confidence that this motor will be serviceable for the foreseeable future. Time will tell. My new mechanic did suggest using the thermostat blanking sleeve to force a bit more water through the cooling system and I will make this change soon. I am planning to take the car on a run tomorrow and see how it fares. I do appreciate all the experienced knowledge offered with various means to monitor and improve conditions such as timing, etc. All will be figured out in good time. I will post some photos of the engine bay later this week and keep my English friends in the UK posted on my California 'original restored' MGA 1500. Thanks all...Safety Fast.

Steve Lofaro


Stephen Lofaro

This thread was discussed between 15/04/2016 and 17/04/2016

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This thread is from the archive. The Live MG MGA BBS is active now.