Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Replacing Plus8 coolant

Can anyone offer advice on replacing coolant in a 2003 Plus 8? Is it as simple as undo the main rad cap (not the overflow) and then undo the drain tap underneath the rad at the bottom?

Or are there some hoses to slacken to avoid airlocks?

I must confess I am only doing this after n years, where n is a very large integer....

Many thanks

Easy enough to empty, just take the bottom hose off the radiator and it will all gush away...............
Whenever I refill any car, it takes ages to get rid of the airlocks and I usually end up bleeding the heater by partially removing the top heater hose with the engine running - it hisses like a central heating radiator. If you jack the front up so the rad cap is high, you might be OK.

If your refilling with standard water/anti-freeze mix then DaveW's method is fine, however if you are replacing with Evans waterless coolant you need to get all the water out and then use their flush, empty again and the fill with the waterless coolant. Drain using the tap on bottom of rad, undo rad cap and filler plug squeeze large hoses to ensure water is expelled check expansion tank and undo it's cap, I would remove it and empty and refit.

I have not used Evans and on my +8 not sure I need to however got to a constant 95-100C today running around at 50mph in Devon, but only when in traffic once moving went back to 90c. I do remember reading about using a freer flowing thermostat that allows the water to be pumped better to the rad and around the engine.

Ps if you do use Evans I would be interested how you find it.

I usually use a garden hose to flush the rad, block & heater.
Particularly if the heater is mounted high, I remember a Renault 5 we had produced tons of brown sludge out of the heater box but after that the heater worked.

As my drive is on a slope I use that to help the air out instead of a jack.

It is probably worth changing hoses when you do it they ofen seems to fail right after refilling.

John - agree with the hose. I also "back flushed" recently after the water running clear in one direction - seems to remove some more

Agree with all the methods described. One thing I learned on TR engined +4s: the engine petcock drain does not necessarily mean ALL coolant is drained. I pulled the head on "lismore" last summer after draining on the level, and then jacking up the front so I could get "better" leverage lifting it off. Surprise! There was still coolant left in the block, enough to wet no. 4 cylinder. Fortunately, the piston was down so I quickly stuffed the bore with a clean rag, soaked it up, and dried it out with compressed air. No apparent harm done, installed the rebuilt head (no. 3 cylinder had a broken valve spring, sucked a valve). These engines have wet liners, of course, so at the ready one must have some hold downs set to fit the studs on adjoining cylinders to keep the liners in place and sealed. Once the hold downs are in place, then the crank can be turned, etc.

But after filling with fresh coolant, I find it takes a couple of ten mile or so runs to move the air trapped in block. I have a pressurized overflow system with a 8 lb double sealed cap going to a recovery bottle. It gets a workout during this period, but finally tops off. hth, cheers gordon "lismore"

Thanks Adrian, ironically my local car club just received a presentation about Evans coolant. Impressive claims but I wonder if it's really justified for "normal" use.......plus I'd be worried about losing it all if a hose fell off. If I was racing, or maybe had a completely new engine to install, I'd consider it but the conversion process from a 'wet' system is quite involved. Maybe I'm just plain lazy.

There are a lot of views on Evans coolant on the web; do a search for reviews. Most of the 'for' views are not very scientific and largely are a justification for the high price of the stuff, and the rigmarole in getting the water out. In other words, I've spent a lot so it must be good. I did find a scientific 'against' view but it has to be said, the writer has an interest in more normal antifreeze.

It may be a good thing for a museum vehicle as there ought not be any corrosion, but I have my doubts for anything that is used, especially raced since the heat capacity of the coolant is reduced.

Not having had one, but I understand the +8 is often a bit marginal on the cooling front, and anything that reduces it, ie a coolant with less specific heat capacity, is not a good thing. Plenty of owners use 'water wetter' to effectively increase the specific heat capacity. Extension brackets for the rear bonnet catches to increase underbonnet airflow seem a cheap, easily fitted device and I've seen plenty of racers with them.

Exactly my thoughts, if I was looking to lower running temperature then the first port of call would be a larger aluminium rad and a more efficient fan. Losing expensive coolant is not a route I would choose and has put me off Evans.

Now I'm finally getting around to doing this, I noticed the 'main' rad cap (not the overflow) is a strange Motorcraft part without the conventional "ears" and has "DO NOT REMOVE" written (in four languages) on it. This may be a dumb question, but that warning is not to be taken literally, correct? (other than when the engine is hot of course!)
If it is, how would you ever refill the system ?? Clearly, with the overflow tank cap sitting lower than the main cap it would never fill that way other than by many repeated uses of the back 'hot syphon', and while jacking the car helps release air locks it's never going to be possible to fill other than via the top hose - surely not? - or the main cap