Running a bit hot

mustang68

The mustang has been running a bit hot of late, the rad, fan and stat all running fine. As a general question what would be the likely culprits of this ? (note: I have some ideas, but I like to hear other peoples thoughts without sticking my oar in)

Also how would running too hot manifest itself, other than temp gauge? (similar note to above)

galwaytt

..when you say rad is 'fine', what do you mean ? Not leaking, I'm sure, but as I found recently on my old yoke (968), once it gets on a bit, and with big miles (163k miles), some of the core passages were actually partially blocked.......

There's no way of knowing, from outside.

I know of a friend restoring an MGB too, and even though low mileage (only 18k kms !) , the core was badly blocked, as was heater matrix. All reduce volume and flow of coolant, which works against you.

bbam

Definitely scale/gunk in the core will reduce the flow through and thus reduce cooling... Agri descaler can be used as a diy cleaner..

I've also heard of the channels in the block/head gunking up in a similar fashion...never seen it though

It's also worth checking the air flow through the core, leaves, flies, paper, grass all get embedded in there and with repeated wetting from rain and heating it sets hard... less air = less cooling..

gn3dr

Yes definitely worth flushing the rad - in fact the whole cooling system. I used some professional stuff I got inn a motor factors once on a Cosworth. The rad looked fine but when this stuff was used it cured the problem (the cooling fan would not come on even though the temp switch was working.

Of course it could also be one of your head gaskets on the way out. (V8 I assume)
Is it losing any water?



Water pump could be failing.

Does it have a viscous coupled fan - if so the coupling could be on the way out. I know you said the fan is OK though.


Final thing I can think of is fuel mixture. A car running lean will run hotter but usually there will be a bit of backfiring as well from the slow burning lean mixture.

Ballykine43

You ask Also how would running too hot manifest itself, other than temp gauge? (similar note to above)
Are you actually noticing anything other than the temp guage reading high? I don't know the setup on a mustang but your guage or the temperature sensor could have gone faulty.

Big Nasty

It's all pretty much been covered apart from one thing - air temp! It's been bloody warm and humid the last while, heck we've been using only a sheet in the cot the last two months!

There's an additive you can use will bring the temp down by approx 30F:
http://www.summitracing.com/parts/RED-80204/

COB MGV8

My V8 used to suffer a little from this as well.

Is it hot at all times or only in traffic ?

Possible Causes :

- As the earlier poster pointed out - is it actually hot - i.e could the temp guage be knackered ? Get your hands on a multimeter with a thermometer or one of those fancy laser thermometers
- Does the Mustang have thermo. cotrollled fans - if so do they kick in ? How old are the fans - are they making any noise when running. Is the alternator ok ? if its slightly suspext, it may not have enough juice to run the fan(s)
- Blocked rad -already covered above
- Low coolant levels - caused by leaks or evaporation - any signs of sediment on any of the hoses ?
- Type of coolant - are you using 100% water - 100% coolant, or something in between. I have used water wetter successfully in my rad for 3 years without issue - my engine has to run 100% coolant becasue its made of aluminium.
- Have you drained the system lately - could it have been airlocked when you refilled it ? (does it change the tem. when you switch on the interior heat?)
- Head gasket - any milky residue on the oil cap ? or any oily deposits in the coolant ? This is an indicator and a negative result does not necessarily mean that you have head integrity
- Have you changed the fuel mixture or ignition timing recently - these can have a bearing on the temperature you are running at - the leaner the mixture - the hotter she runs. (different plugs in use?)

mustang68

Wow, that is the most comprehensive reply I've ever seen here! I'm going to bookmark this as I think that everything anyone needed to know about overheating is covered here. This is why I love classic cars on boards, input from people who own all sorts of cars, not just a blinkered view of a certain make or type.

I'm not going to get though all of the points here, but the guts of it is that my overheating seems to have been a combination of timing too far advanced and running a bit rich, thanks to everyone here for helping me with that.

The car: v8 289, with electric fan, computer controlled EFI, electronic ignition.

Things that were wrong: Temp gauge showing hot (temp taken in engine block), fan kicking in a lot (fan sensor in rad), car running rough in high temp, fan usually got it down quick enough, some backfiring after very hard acceleration, engine bay and passenger compartment quite hot.

I've dialled back the timing and it was much happier this morning, i'm also going to richen it up a bit, I leaned it out recently as it has been bad on fuel, but I think that was false economy.

I'm going to run some rad cleaner though it in a few weeks to flush out the rad as suggested, a water pump could do with a change too, syptoms are the heater not getting very hot (although the core of the heater is brand new).