Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Coolant Volume

I have recently flushed the cooling system on my Plus 8 and have refilled with coolant. I filled it up until I could see the fluid at the top of the radiator then ran the engine for 15 minutes then topped up again. It appears that the level is still adjusting and I keep topping it up since the level drops and is not visible in the top of the radiator (no fluid is seen in the expansion tank yet - the line to it is clear). So far I have added ~6 litres of fluid. There are no leaks in the system and I am sure there are no leaks of coolant into the engine since the oil seen at the dip stick is still clear and bright.

Maybe it just takes a while to get all the air out. Maybe a water wetter would have helped. Appreciate any insight from the group.

Thanks,
David

David,

I'm sure this is just the coolant gradually filling various areas of the system which have airlocked. My 1993 +8 does exactly the same thing, and it can take quite a few hot/cold cycles before coolant remains in the expansion tank on cooling down. This is especially so if the "heater" (a euphemism if there ever was one) has drained down. I've never tried a water wetter, but I'm sure that someone on here will be along soon to describe their experience with it.

Dave

Thanks Dave. Mine is also a 1993 Plus 8. I will keep topping it up until i establish a level in the expansion tank. Will keep a close eye on it over the next few days.

Thanks for your input.
David

Plus 8s were a right nuisance filling with coolant when they first appeared. They were using the first Rover V8s that had a "teapot filler" suspended on the top hose between the rad and the engine. Made quite a mess.They would tell the owners to jack the rear of their car to fill the radiator! Air in the cooling system was inevitable. The bubbles in the system were so large they could even push the coolant away from the coolant temperature sender at the top of the engine. The resultant readings would scare everyone. I occasionally muse wonder whether that is why the MMC placed the rad fan switch at the bottom of the radiator when the temperature sender we read is at the top! Eventually they recalled all UK Plus 8s and that was end of the teapots. I have a picture of the Pickersleigh pile of them somewheres.

Your coolant capacity according to your Manual, is 9 liters. But it is rare you will get in that much.

After a couple of preliminary years of annoyance, a LONG time and 400,000 kms ago, I developed a system for Plus 8s. Never fails me.

1. Firstly, I use a expansion method rather than a recovery one. It merely means placing the pressure cap on the reservoir rather than the radiator. Expansion tanks MUST be higher than the radiator and that is why most +8s have the reservoirs on the bulkhead, the highest point in the engine bay. I cap it with a safety pressure cap at 15 psi, as the manufacturer suggests. I do not use any higher because I have no wish to put any more strain on the water pump than recommended. And additional benefit is that you will be able to depressurize the system, faster and safer at the reservoir than the rad. But always be careful.

2. The radiator is capped, not with pressure cap but with a shut-off cap (available at any savvy LR/Rover supplier) These caps are not pressurized and leave the line to the reservoir unobstructed.

3. When filling the rad, I do so to the top with a distilled water solution. (50-50 coolant-to-water to which I add a bottle of Water Wetter (which really does work, just not as enthusiastically as their advertising..figure -2C better).
My goal is to keep my car within the operating range recommended by the manufacturer. My goal is NOT to stop it boiling over when it has to. (only once in 30 years when I joyously blew a head gasket in the Dordogne). Stuff like Waterless Coolants allows the engine to run WAY over the manufacturer recommended limits for engine health. We should WANT the engines to boil over if something is amiss.

4. Once I have the rad filled to the top. I wiggle the car by pushing it to make the rad move a little. Bubbles will stream up to the rad entry. I do that until there is space and I fill again. I repeat the process 3-4 times until there are no bubbles.I close the rad with my non-pressure cap.

5. I then move to the expansion tank. I fill to 1/2-to 2/3ds. Remember, you will be filling the hose from the rad to the expansion tank as well. I over fill to this level to make sure any air I missed will be filled by the excess over the 1/3 of the reservoir which I am shooting for after the system has adjusted. Anything more will be expelled by the system after a drive or two. Any needed will drain the reservoir, so add a little after chaeck after 2-3 days.

Good luck.

It’s a shame there isn’t an air bleed valve in the top hose from the radiator. I had a Renault with one and it helped immensely to bleed air from the high part of the system, where it migrates to.
On the Plus8 (2002 model) the method above was basically what I used. My expansion tank was near the rad, not on the bulkhead though. I unbolted it, raised it up and it helped by being higher. Replaced when happy that airlicks were gone/ greatly reduced.Slightly overfilled to allow coolant suck-back as air was removed. Squeezing the top hose also helped get air from it into the expansion tank. Keeping the level in this expansion tank is important to stop air getting sucked back. Any excess will be expelled via the overflow pipe in the filler neck. The cap (15psi) released to let the excess flow out. Later level checks made after a few miles driving. I used 50/50 coolant/distilled water with water wetter.
Mine overheated once when stuck in traffic on a hot day and the fan fuse blew. Replaced the fuse and checked the wiring/thermo switch etc but no problems after that. The fan was always loud when on so an audio back-up to alert temperature getting up! I did some small jobs to reduce this. Making sure as much air as possible went through the rad ( Morgan ali not aftermarket). Morgan airflow leaves scopes for improvement! I believe the rad was slightly under spec as a heat exchanger as it was too near the limit for the thermo switch to kick in. The core should have denser gills per inch to increase hear transfer/airflow surface to marginally increase heat exchange, or even an extra row of tubes that would further increase heat exchange. This would reduce the times the fan kicked in. No overheating but enabling a slightly lower ambient running temp would give bigger leeway to the fan kicking in. Both these are standard upgrades. We used these in the radiator factory as basic upgrades for different engine sizes/ oil cooling/aircon differences for Rover SD1 cars as OE equipment for the assembly factories.

I fitted one to my 4/4 into the heater circuit. Fitted a longer hose so it was above the radiator and heater matrix at the highest point, and put a bleed valve point in. Not sure if it's possible to do something similar on the +8

I too use the expansion pressure cap on the recovery tank method, although, there are many who will tell you that is wrong and the pressure cap should always be on the radiator. Air bubbles are prevalent in this era of Morgan cooling and the above method is a good way of dealing with them, it also means all the fluid filling and checking of levels is done at the recovery tank. The system will burp air and fluid out of the recovery tank finding its level, works a treat.

Even some later Mogs suffer airlocks, this is a pals 3.7 Roadster with the heater hose routed over the top of the engine, even higher than the expansion tank, since fitted a bleed valve (not shown) which has sorted the annoying airlock forming during winter lack of use

Dear Britmog,

Thank you for your feedback. It is invariably helpful.

There will ALWAYS be some who tell you are wrong. They don't really understand why, but they will say it anyway. If they do know why, and convince you, as we say in Quebec tant meiux!

Bad advice goes viral. And I stubbornly used a pressure cap on my radiators for 10s of thousands of miles and a few years. PIA. Then, in annoyance, I started collecting Rover/LR Factory Workshop Manuals and experimenting. They showed my method described above! However, you can find Manuals that will say anything one wants. BTW, after years at this stuff, I no longer trust "everyone" or supplier assurances or Manuals. Forgive me all. At best, Rover/LR Manuals merely indicate what someone, with less mileage than you and nary a Morgan thought at some much earlier point in time, before a few million miles had been logged by the relevant owners' community. In my case, as John Sheally 2 used to constantly say on eMog, "I speak from experience. I am unoffended if you choose another way." One can only truly learn from mistakes.I have made a ton over 30 years. However, the only other person I have ever met in our community who had no hesitation in tossing any method or components regardless of their cost IF it did not improve his Morgans, was Bill Button. Weird eh?

In sum, NOPE. This method works on all trad Plus 8s who have tried it. It has something to do with the engine configuration in a Morgan but, as usual, like everyone else, I have a tendency to move on when I found a solution. I used the best method, trial and error. Later Plus 8s moved to a bigger tank placed adjacent to the rad.

I forgot something important. I began with the Sd1 reservoir (below) standard to all Morgans of the day. Pitifully small affairs. https://rimmerbros.com/Item--i-CRC4058 You will note how they ALL refer to the thingie as "an expansion tank". It was attached to the bulkhead I moved to my first aluminum rad, only one available, a Griffin from the USA. I swapped their expansion tank in at the same time. Double the capacity. I moved to a Mulberry the day he came out with one. Later Plus 8s used bigger tanks as well. The Factory had wisened up. They also cleared it away from the ever more crowded bulkhead and placed it next to the rad where it could get nice and hot. Not their fault. The miracle of the MMC is how they kept these cars compliant for so long! However, the newer placement of the expansion tank appears to violate the cardinal rule that an expansion tank should always be higher than the top of the radiator. Deadly Domino Effect strikes again!

gmg

P.S. These are many little tweaks that are costless. They remove annoyances and make your Morgan happier.

'

Excellent input as always.
Most appreciated.
David