Morris C8 radiator
 

Had a drive of my Morris C8 today and it blew out a hell of lot of coolant about twenty minutes into the drive, the sealant to seal the thread may not be the required temp spec so I would ask of you all is there a high temp sealant that will do the job?
Paul

coolant
 

Paul

Can you explain the issue in more detail ? Where is the "thread" you mentioned ? Is it the drain tap thread ?

Mike the threaded ring has to be 9/16 from the top and sealed with I hope silicon sealer, I have been having problems with this leakage since day one and Richard Farrant has been helping me along with it. I will try some plumbers thread sealant today as that can stand fairly high temp.
Paul

radiator
 

Paul

I have around 6-7 Morris CS8 and PU radiators and I not seen that type of cap on any of them :confused My caps are a simple brass cap with a internal thread , thats it , no spring .

Thanks Mike and I have installed the cap assembly with some loctite high temp sealant and have left it for a couple of days to go off and will fire it up this morning, very hopeful it will do the job. In your radiators what releases the pressure?

Air-Lock valve
 

Hi Paul,
This Air-Lock valve in the filler was also used on some Bedfords, like my QL. After owning it for about 30 years now it has never given any real trouble then about 3 years ago it started blowing water out of the cap intermittently and I removed the complete valve and checked it over. The spring had rust on it and was stopping full pressure of it onto the sleeve and sealing ring. I also found the screwed ring was not set correctly. Once I sorted this all out, and filled to the correct level (a bit lower than before) the blowing out stopped. Temp gauge only showed normal temp when water blew out, so doubt it was overheating.
Hope this is of some help.

regards, Richard

pressure
 

As far as I know there is no pressure, its a thermo syphon system with the water pump as a backup :) The radiators on these trucks are large and wide . Maybe Richard F can provide more info ? Thanks Richard over to you :thup2:

Hi guys and yes I went for a few runs in the C8 and on the last one it blew the coolant out which was a major disappointment, I do believe it is the spring as mine isn't bound with energy and the filler funnel was pitted but I honed that but it is wearing a bit thin. Any idea of NOS for those two? My temp gauge was on normal middle setting so it wasn't over-temping in fact it only took about ten minutes for it to be ok to refill prior to going home, :whinge
Regards
Paul

pressure
 

What is the pressure level you have just before it blows ? Might be worthwhile fitting a pressure gauge on it and go for a drive . The spring might be functioning correctly and doing what it is designed to do, release pressure above a certain psi.

Will check in the morning as I looked at the needle just before it blew but it wasn't past the middle of the gauge, I was only going slow and when I got back home I let it settle before switching off. It was fine, with all this coolant on the engine it shorted the spark plugs and caused a couple of backfires. I have the original spark plug steel caps so I will get some rubber caps tomorrow as the back fires cause the exhaust to split, I have been through two exhausts so far. Will keep you posted.
Paul

Checked the temp when the rad blew and it was only 140 which isn't running temp, on these old vehicles is 160. I have stripped out the assembly and cleaned and honed everything, I reassembled and screwed the ring past the 9/16 mark then applied the sealant which worked very well on the previous go and screwed the ring back up till on the 9/16. This makes the rubber seal and funnel seal that much cleaner and sealant only on the threaded part. Will give a day to get the sealant to set then give it another go.
Spring isn't the best I feel.
Paul

. In theory if the spring is weaker than is specified, it will release pressure before it should do i.e. at a lower psi . Yes try replacing the spring .

Yes Mike I will give the C8 another run possibly Wednesday and if no luck then I will be appealing to the MLU for new old stock spring, filler funnel and a rubber seal, I have been on ebay for some spark plug rubber caps and have repaired my exhaust box. They make these exhausts out of soft steel these days as I bent the joins with my fingers, when all is right I will replace with stainless.
Regards
Paul

Had for a run in the C8 and yes it blew out the coolant again, as soon as it started I stopped and let it cool off filled up and got home. A major setback so I am on the lookout for a new spring, filler tube and rubber seal. I have contacted Wheels & Tracks who seem the most likely but no reply yet, if anyone has these items I would be pleased to pay for them.
Paul

spring
 

That's bad luck . Must be frustrating for you each time it plays up like that.

To be honest you will have to experiment with a replacement spring from somewhere that is close to the original specifications. Rolf Ask in Norway had a container load of Morris NOS stuff , mostly 4 cyl. but. where it all ended up is anybody's guess. He had new radiators and even a NOS engine block plus many other items, all ex Norwegian Govt. stock .

NOS parts for these Morris trucks are very thin on the ground just about non-existant. The CMP guys don't know how lucky they are !

Mike more than frustrating but sort of get used to it, been in touch with a couple of sources but nothing yet. Maybe try one of the spring makers if I get blanked out as there are a few of them that do individual springs, I was going to take the C8 up to Bundy for our MJCQ club weekend next week but the Austin champ will do nicely.
Regards and will let you know of any success.
Paul

Hi Paul,
I have found some info regarding the Air-Lock filler as fitted to your Morris, and Bedford QL. It is not a pressurised radiator. There is no overflow tube as in some radiators. To quote:
"To prevent dilution of antifreeze caused by careless topping up, an 'Air-Lock' type radiator filler is fitted. This filler incorporates a spring loaded valve in the filler tube which permits steam to escape through relief holes in the cap, no overflow pipe being used. The filler cap must screwed right home to open the air lock valve in the filler."

I had similar problems a few years back on the QL and was not filling the rad more than in the past, but I did find the thermostat was stuck open and wondered if it had been playing up and sticking shut as well. Water would blow out and coolant temp was normal, it would then stop blowing out and run normal until it would happen again for no reason. I changed the thermostat and stripped and cleaned the Air-Lock, did find the adjusted ring depth was not correct, so reset it. Watch that you are not overfilling the rad.

regards, Richard

Thermostat
 

I agree with Richard and we should have thought about the thermostat ages ago.

My C8 ( the little CMP 4X2 ) would blow coolant out the radiator cap with some force , usually after climbing a hill. At the time, I was running it without a thermostat :doh:.

The thermostat does a important job , but it has a second function, it restricts the coolant flow into the top tank , without this restriction, the coolant fills up the top tank and eventually pressure builds up and it blows out.

I would check your thermostat . Is it the correct type ?

My CS8 4X2 has a different cooling system . They fitted your type to the 4X4's .

Guys there lies the conundrum "no thermostat", don't use them here in QLD but maybe I will need to find one! I purchased some bronze today and will make a new filler tube and castelation ring on Wednesday, I am borrowing a friends lathe to do the job. The spring I am sending to a company in Brisbane to make a stainless replacement as no-one does bronze springs anymore, I haven't overfilled with coolant as from your early advise Richard I just touched the core and at least 4 litres of coolant blows out so it is excessive and that is with stopping straight away. It is interesting that it blows as the temp gets to running temperature so the thermo theory could be correct. Any idea on spring tension?
Regards
Paul

bronze
 

OK sounds good . Bronze isn't cheap . You could try making a new filler tube from aluminium as a 'test run', doing this will also check your set up in the lathe. Then if the alu one fits OK , go for it with the bronze . I'm always nervous when machining a piece of expensive metal , one slip up and its junk

Hi Paul,
The brass ring should have a rubber sealing ring bonded to the lower side, is this missing on yours? Remember this does not seal the radiator cap, it only seals off the air gap above coolant in the header tank when you remove the cap to check the level, so you do not overfill.
Another thing that gets overlooked is the fan belt, is it gripping and adjusted correctly. Some British vehicles used belts of a different V angle to the standard A, B and C varieties. You may have to compromise, but worth checking as belt may be slipping at times.

I am a bit puzzled by this discussion. I have two Morris C4 for the moment and didn't find a thermostat in any of these two engines and even don't can find a notification about a thermostat in the workshop manual.

On my C4 the airlock valve was missing but luckily I did found a complete set up in Norway.

on the left side of the picture you can see the air lock set up.

thermo
 

Even If a thermostat is not an original item in the 4 cyl. engines , it is worth Paul trying a thermostat as an experiment because it might be the answer to his issue. Are there any more of those NOS parts from Norway available ? It has been ages since I last heard from Rolf.

Without a thermostat in the C4 , there must have been some kind of restriction in the coolant outlet from the engine, limiting the coolant flow to the header tank . The thermo syphon system requires that there is a significant temperature difference between the engine and the radiator , this difference aids the coolant flow . If the engine and the radiator are at the same temperature ie no thermostat fitted , then that is not ideal and can lead to problems

That's a fine answer but what about the non existed thermostat in the workshop manual ? for sure i think a thermostat is the best way to go but on these engines I have I don't can really find the provision to fit a thermostat ??

Hi gentlemen and where do I start, machining isn't a problem as it's been my trade since I was 15 so no issues there it was just getting use of a lathe, the current castelatated ring has a rubber seal although the reason I am making a new ring is the one I have is distorted due to hammering the thing to remove it over time also I will make the funnel with a thicker flange to stop warpage. I have lapped the ring but where the rubber seal sits it has high spots under the castelation points and these high spots can prevent a good seal. I also have new rubber to make a new seal when all is done, in regards to the thermostat it does mention one in the manual but for only "quick warm up reasons" and not for any pressure holding in fact the engine has a bi-pass pipe that goes around the thermostat. I will send my spring to a company in Brisbane on Monday as they reckon they can make a stainless replacement, not sure the new pressure of this spring will have any adverse effect but my reasoning would be it will greatly improve the seal at this point. Fan belt is working and no slippage noted. The manual doesn't show the thermostat but does mention it so I for no other reason than elimination of a problem would like one if anybody knows where?
Thank you all and I am open to all advise, thanks for the photo Guy and my assembly is the same as yours.
Paul

Hi Paul,
The only thing that lifts the sleeve off its seat against the spring is the screwing down of the radiator cap, to allow steam to escape, so spring rate would not appear to be too critical.

regards, Richard

Thanks Richard and further to the enquiry on the fan-belt adjustment there isn't any I can see, I took it off when I did the cylinder head and just couldn't remember seeing adjustment so will have to get another belt just in case. The thermostat I imagine will be the same as the champ one? I will check it out as they are still available and the only thing I didn't mention was the cap was down tight.
Regards
Paul

That's the right water pump for a Morris 4 cylinder engine , you can see that there is a adjustment on it.
The adjustment is done by getting the two sides of the pump pulley closer together so the V belt is running higher on the pulley.

Hi Paul
As you were not aware of the adjuster pulley on the water pump then it might well be that the belt is not tensioned enough, as one of my suggestions earlier.

Regards Richard