Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Plus 8 overheating

My Plus 8 overheats after sitting in traffic for a few minutes.
I have done the following
Checked the radiator fro clear running
Fitted new 14 HD fan
New Thermostat at 82 degrees
It has an oil cooler as well
Checked Timing at 6 degrees BTDC
Putting the internal heater on full blast delays the overheating but not cure it.
Help any ideas?

Lots of Trad Plus 8 owners add a fan override switch, so you can turn on the fan manually as you hit traffic, before things get critical

The ultimate cure would be to replace the OE radiator with an aluminium one, but you'll be looking at £600 ish

There are a number of things you could try:

- check the system is properly full of coolant, with no airlocks. I am not familiar with the Rover V8 but would guess there are recognised filling methods to avoid airlocks.
- check the rad is clear of debris: road oil and muck can significantly down grade its cooling capacity even though it might look OK.
- check your fan belt is properly tensioned, so the fan is cooling to max efficiency (if fitted with a mechanical fan).
- backflush the entire coolant system: rig up some pipes etc so you can run a hose into the system against the normal flow, leave it for a good 30 mins.
- try some coolant additive such as Water Wetter.

If no joy, some more expensive options:

new water pump
new alloy rad
new additional electric fan - Revotec or Kenlowe (or is this what you mean by 14 HD fan?).

ON another make I also know someone who fitted a small electric pump into the bottom hose, wired through a relay to a switch. He uses that to keep coolant flowing through the system when stationary. It's a pre-war car so prone to boiling.

I had a similar problem with my 1997 3.9L +8, just over eight years ago. After some home work I decided to fit a Mulfab aluminium radiator also fitted 14” electric fan. Then as the cooling system was empty I decided to refill it with Evans waterless coolant. I do realise this was a bit of a controversial decision and some people will have different views on this.
But I have to say, it might have been over kill on my part, but it sorted the problem out and so far so good.
I hope you find this of help and manage to sort you overheating problem out.
Good luck
Regards
Steve

Have solved the problem on both my +8s by fitting revotex thermo fan control in the upper rad hose.The 1995 3.9 had the
previous thermostat In the lower offside side of the rad (aluminium).
The 2000 4.6 had the thermostat in the upper nnearside area( aluminium)
Problem solved 100 per cent on both vehicles
No connection to company but very happy

The little extender brackets on the rear bonnet catches help a little too.

Can you feel any cold hoses when its up to temp? they should all be hot/warm

When you say it’s overheating can you please be a bit more specific?

Is just the fan coming on and staying on? (mine does in traffic), or is it actually boiling over and you’re losing coolant? What is the temp gauge reading?

I have a Mulfab radiator, and have wired in an over-ride switch so I can bring the fan on a little earlier, like when entering a built up area, and have just fitted a pair of bonnet catch extensions. Mine doesn’t lose any coolant and we often have 30+ degrees here.

I agree with the above, what do you mean by overheating, is it just running hot according to your temperature gauge and what do you consider to be hot, is it losing coolant? Morgan temperature gauges are notoriously inaccurate you need to take a temperature reading using a laser thermometer. What year is your+8, the Rover engine runs hot and needs too so comparing to what other cars run is not an accurate comparison? Installing a fan override switch is a simple and useful upgrade for when driving in hot conditions such as slow traffic or in my case very long twisty steep mountain passes that put the engine under heavy load. If your engine is carbed then the thermostat should open at 82c if it is EFI then the thermostat should open at 88c.

I agree with many of the comments above, but can possibly add a little from my own experience.

The later versions of the Rover V8 were designed to run very hot in order to minimise emissions, so the margin between "normal" and too hot is much reduced.

What pressure cap you have on the remote expansion tank? Check that the rubber is not in poor condition. A 13 psi cap will elevate the boiling point to well over 100 Deg C. There should be no pressure cap on the radiator itself.

As Mick says, is the gauge showing temperatures of over 100 , or is it actually boiling and forcing coolant out through the reservoir overflow pipe. As per Bruce the Morgan gauges are highly inaccurate and may be reading well over (or under), usually depending upon the quality of the earth. An indicated temperature of 110 is not normally anything to worry about.

Is the electric fan wired up the right way around ? If in front of the radiator you need a "pusher" , and conversely behind the radiator you need a "puller" Easy to get the wires reversed and on some motors this will result in the motion being the opposite of the desired one.

The oil cooler should help reduce coolant heating by conducting heat away from the engine. A larger ali radiator is a very sound investment , but not cheap , the bonnet bleed brackets will also help a little.