Frustration! Overheating.

David2021
Posts: 137
Joined: Sun Jan 31, 2021 5:29 pm
Location: Stratford upon Avon

Frustration! Overheating.

Post by David2021 » Wed Jun 08, 2022 8:15 am

My 12 tourer is misbehaving!
About 3 weeks ago the manifold to head gasket blew at the back after a brisk 15 mile trip. Before this it was running well.
Gasket replaced & manifold fitted with new downpipe studs. To do this the Solex came off & was put back (after testing the secondhand SU.)
The car ran poorly. It would not idle and no adjustment of the slow running jet seemed to make any difference. As I had to have the car working to get it up to Nottingham I set it on a fast, lumpy idle, which felt & smelt rich.
The car was booked into PD Gough to have a new exhaust made & fitted yesterday.
Set off early and after about 50 minutes of normal driving (motorway 55-65 and other roads at speed limit speeds in convoy with my grandson in the ZA Magnette) the car abruptly boiled over- spraying water from the radiator capon a dual carriageway. (My temperature gauge is not reliable!)Topped up with about a litre. 5-8 miles on....repeat...again. Now our reserve water was used up so drove gently (30-35) the rest of the way with one more top up when refuelling. This stopped the boiling over, but the car felt lumpy & uncomfortable.
Goughs made & fitted the exhaust (EXCELLENT SERVICE) a separate post will follow. They found a 40 litre container for water and I set off home to Stratford on Avon. Car ran as it had when I left home, and I kept he speed down to 45-50 but shortly after joining the MI it boiled again, and again, and again (Getting boring now)!
I found that by keeping it at 40-45 I could get about 10 miles. When I came to the las 20 more cross country miles to home I kept it to 30-35 and did the last 20 miles without drama. It rook 2 litres when I got home and was gurgling merrily. Oil pressure fine, radiator gas a bit of a cool spot in the middle by the fan boss.
When I got the car I knew it overheated, but found it had no thermostat. Fitted one & have covered 1000 trouble free miles, including motorways. hills etc up to now!
I will do a compression test (cold & Hot) this morning, and see what the plugs look like.
Any ideas....I am still planning to take it to France etc at the end of the month....., but am not optimistic.
David

rgburlend
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Re: Frustration! Overheating.

Post by rgburlend » Wed Jun 08, 2022 9:36 am

That is rather annoying. My 14 had a problem with overheating when I first put it back on the road. When I bought the car, I was told that the radiator had been recored, and I agree that it had been done but so badly that the entire radiator was rendered scrap. I was given a second radiator with the car so I decided to have this unit reconditioned by a classic radiator specialist. When i took it into his workshop, he looked at it and said Rover P2 straight away so I thought I might have found someone knowledgeable on the subject. However after two months, nothing had been done and after a third month, I returned and collected it untouched.
Thinking about it, I decided to remove the bottom tank myself and see what state it was in. I should mention that I had tried to fill it with water and although it didn't leak, there was barely a trickle of water passing through it. I heated the bottom tank and prised up the lip that crimps the tank on to the core, which of course, immediately cracked off.
The amount of rusty silt in it was amazing and I ended up making a spade drill out of a welding rod and drilling the silt out of the tubes, then using a strip of silver solder which was close to the internal dimensions of the water tubes to rod every tube out. I resoldered the bottom tank using a U shaped brass section to replace the missing lip.
On fitting the radiator, I was delighted that the car ran much cooler than before and so far (5000 miles) has not overheated. I did take the precaution of fitting an automatic electric fan at the same time and a new thermostat modified to open the main flow, simultaneously closing the bypass port a very important feature, I also fitted new water pump bearings and water seal.
I suspect that the cause of your problem might well be similar, I am assuming that you have checked the ignition / distributor. I doubt if the carburation problem would make a significant difference to the engine temperature that a working cooling system couldn't cope with.

David2021
Posts: 137
Joined: Sun Jan 31, 2021 5:29 pm
Location: Stratford upon Avon

Re: Frustration! Overheating.

Post by David2021 » Wed Jun 08, 2022 1:44 pm

Thanks for that helpful information rgburland.
My confusion is that before the manifold gasket blew, the car ran very well. No overheating since putting in a thermostat!
The radiator maybe could do with a clear out, (as perhaps also the block) but it worked well until three weeks ago!
The only things that have been altered are the carburettor removal & putting back and attempting to make the slow running work! and the manifold gasket. Is it possible that something has been dislodged in the carb? could the "starting carburettor be stuck "on" causing an enriched mixture....but would that cause the engine to overheat to the extent that it boiled over...? Unlikely I think.
Of course co-incidentally the 12 month old Thermostat might have failed...? The water pump seems to be working as once when I stopped with steam coming out below the cap and the engine off., I restarted the engine and the boiling subsided, suggesting that water was circulating
Keep coming with ideas!
David

Willem
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Re: Frustration! Overheating.

Post by Willem » Wed Jun 08, 2022 10:25 pm

Hi David,
just a thought, could something have dropped in one of the cooling galleries whilst the was head off, managed to get lodged in the feed to the radiator reducing the flow? As for the idle problem, could the fuel be evaporating in the fuel line due to the block getting too hot? Just my thoughts
Rover 12 Tourer, 1936
Range rover L322, 2009

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luli
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Re: Frustration! Overheating.

Post by luli » Fri Jun 10, 2022 12:06 am

To me it looks like a damaged head gasket. The lost water is a strong indicator. See more here:
https://lulis.org/2016/11/10/%d7%92%d7% ... %a8%d7%90/
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
http://lulisml.wordpress.com/

David2021
Posts: 137
Joined: Sun Jan 31, 2021 5:29 pm
Location: Stratford upon Avon

Re: Frustration! Overheating.

Post by David2021 » Fri Jun 10, 2022 9:07 am

Thanks for the thoughts good people!
Willem. Good to hear from you...the cylinder head was not taken off, just the manifolds, so (I hope) no chance of foreign objects going where they shouldn't into waterways!
Idle problem was a blocked idler jet. Quite a lot of very very fine "sahara dust" reddish in colour in the bottom of the float chamber.
I put all the jets through the ultrasonic cleaner & no rubbish appeared, but the idler jet was cleared! Tick-over now better....I have found that the distributor has virtually no "springback" so new bob weight springs on order!
Plugs (NGK BP6ES) looked as if they were running a bit hot, but no oiling up nor heavy carbon deposits.
The compression check (cold) showed all compressions similar. All about 60 on my gauge....seems low to me, but is the same as when I bought the car.
So I HOPE it is not the head gasket...There was no bubbling visible at the filler neck.
Luli ..I read your accounts with horror! I never much liked Klingerit gaskets, but the C/A one on your tourer was comprehensively blown!
Following discussions at the Club meeting I have bitten the bullet & sent the radiator for a new core...It took about an hour to get to the stage "now lift out the radiator", but I found I had to remove the stone guard and get the radiator shell out of the way.
Doing it single handed I needed 6 ft arms to get to both sides of a few bolts & nuts ( the ones without helpful captive nuts) took another 50 minutes!
Putting it all back I will get an assistant!
I now have to make the Viking face the right way! He is about 35 degrees off centre...

HAD501
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Joined: Thu Apr 23, 2020 10:48 am

Re: Frustration! Overheating.

Post by HAD501 » Fri Jun 10, 2022 6:45 pm

Hello David
A few more thoughts - helpful or otherwise! My previous 12 used to eject coolant in this fashion. It was 25 odd years ago so detailed memory is not available but the solution did involve a new core in the radiator. Also important to have the correct type of thermostat which shuts off the bypass circuit at the same time as opening the flow to the radiator. Still doesn't explain why your car suddenly started playing up though.

More recently, my present 12 had been idle for a while so I decided it needed a run out. It fired up with no problem so I drove off with the cold starter still operative and only later discovered it wouldn't tick over. At first I thought it might be due to the geriatric petrol in the tank, but rigging up a temporary supply with brand new fuel made no difference at all. It turned out to be a blocked slow running jet with a dash flooding thrown in. Anyway I now know it's not that fussy about fuel.

On the subject of compression pressure 60 does sound a bit low. I've had a look in my notes and after 200 miles my newly rebored engine recorded between 142 and 147 (engine warm). I haven't checked it more recently and I've no idea how accurate my tester is.

Good luck with your trip to France - I thought I was being brave taking my 24 year old R8 last month!

David2021
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Location: Stratford upon Avon

Re: Frustration! Overheating.

Post by David2021 » Sat Jun 11, 2022 3:41 pm

HAD 501 Plan B is to take our 25 year old Punto Cabrio to accompany the 1956 ZA Magnette (PFO501 !!!) to a Magnette meeting in Luxembourg!
A question for those who may know.
The Workshop manual talks about "FA" markings on the flywheel at No1 all valves closed.
Is No1 closest to the bulkhead?
My flywheel is marked "EP" when the rotor arm points at No 4 counting from the radiator! I cannot find FA at all... (!) the only other marking is some chewed up teeth!
Any tips on changing distributor springs....

HAD501
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Joined: Thu Apr 23, 2020 10:48 am

Re: Frustration! Overheating.

Post by HAD501 » Sat Jun 11, 2022 5:02 pm

David
I’ve been trying to upload a picture of the flywheel marks but have given up for the moment. The TDC, FA4 and FA6 marks are located close together. (FA6 applies to the old 14hp engine so ignore it). FA4 is 26 teeth anti-clockwise from EP (used for setting the camshaft relative to the crank).
Personally I take number 1 cylinder to be at the front, but I don’t think it matters anyway as long as you are consistent. Probably helps to know what the previous owner used.
I’ll have another go at uploading the pic.
Hope that helps, DavidM

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luli
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Re: Frustration! Overheating.

Post by luli » Sat Jun 11, 2022 5:15 pm

Although it points to #4, the lead should go to #1. This can be rectified easily: remove the rotor, remove the points plate, pull the cam and turn it by 180 degrees. re assemble. Now the cap will point to #1. This correct provided that no body had turned the flywheel by 180 deg.

See more here:

https://lulis.org/2014/05/10/%d7%a8%d7% ... %99%d7%90/

and here (!):

https://lulis.org/2014/08/05/%D7%A8%D7% ... %9B%D7%90/
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
http://lulisml.wordpress.com/

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