So, I was playing around with my carby yesterday (not related to this issue), and turned the van off. Splutter, splutter, gurgle, hiss, and a decent amount of coolant was being spewed out underneath the radiator.

This wasn't happening while she was running, only when I turned the car off. I tracked it down to the overflow hose. I repeated it a couple of times and in only three repeats the radiator has lost all its coolant.

Should this hose be connected to the bottom of the radiator somewhere or is it simply supposed to be hanging down the side of the radiator? I can't seem to see anywhere where it would be connected, but there was steam, so I might've missed it

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'77 Leyland Mini Van

Overflow hose runs down the back side of the radiator, it doesn't connect to anything.
If it is blowing big bubbles and ejecting all the coolant, it sounds like a head gasket problem.

Note if you fill it to the brim when cold, it will blow nearly 1/2 the top tank out as it heats- this is normal. Water expands and has to go somewhere.
There is a level mark 1/2 way up (visible with cap off) on many radiators, fill to there when cold.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I would assume you are running a little lean and maybe the timing is slightly off , you may also have a partial blockage in the radiator , the first thing I would do is replace the radiator cap with a 13 pound cap you can find them at Autobarn etc just take the one you have to compare it , if your radiator cap wont hold pressure your system will find the cap as the weakest point and leak out the overflow , the next thing is check the fluid level in the SU if its low refill with ATF fluid , use a piece of cut off drinking straw to refill ( as in dip it in put your finger over the hole release finger to fill ) don,t overfill !!!

over to you

.

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Thanks drmini, that actually makes sense,thinking about it, it would only be connected to an overflow tank of some kind, if anything! I ran the car with the cap off for a couple of minutes and the fluid had a large bubble once every ten seconds or so?

74snail, I'm about to do as you've suggested. The seal on the old cap is split in a couple of places so this is contributing to the issue, perhaps. As for the dashpot oil, how full is too full?

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'77 Leyland Mini Van

A dashpot can't be too full. It will push the excess oil out the breather hole if it is too full. (my tip, hold a rag on the hole and lift the piston with your finger a few times to push out the extra oil)

cheers, I've been looking for this info the last day or so

Sorry for the highjack,
but can someone please tell me what is the correct type of dashpot oil and where would be the best place to buy it?

Thanks
Curly

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1963 850 (Cooper S wanna be)

Some use no Oil, but its a bit of trial and error
Su Oil, Sewing machine Oil or Auto Transimition Oil

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Stop Licking the Dog...I Don't Care Who Started It

Depends what state of tune the engine is in, also what carb.
The thicker it is the richer the mixture as throttle opened from idle.
Popular ones:
Dexron III ATF (auto trans fluid)
Singer 3 in 1 oil
SU dashpot oil
10W/30 motor oil
none

etc

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The correct oil is SAE 20 oil. Most people run ATF (Auto Transmission Fluid)

Thanks guys.

For the record I have twin 1 1/4 SU's on a Cooper s engine, as far as setup goes my mechanical knowledge is lacking so not sure. I am learning as I go.

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1963 850 (Cooper S wanna be)

Excellent. I always thought I was overfilling the damn thing. Also, thanks 74snail, I think that the old cap was not contributing to my issues but causing them. I'll check it all out tomorrow.

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'77 Leyland Mini Van

We have all been where You are now.
Since Getting back to Mini's I have purchased 2, while keeping one the road I have built another. Could not say how many Hours I have spent on both knee's in that mechanical position for want of knowledge.
Ask Questions & Search, I could not have done it without the people on hear and a close Friends also

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Stop Licking the Dog...I Don't Care Who Started It

Thanks for the reassurance, gafmo.

Sadly, the cap did not fix the problem. I took it for a longer drive (around the block) and it dropped a large amount out again.

So trying to think about this and from what people have already said, when I turn the car off, the radiator fluid is still under pressure and is moving towards the cap as a way out? So most likely I have a leak from the cap to the head?

The radiator fluid turns brown pretty quickly so I'll try and flush it out tomorrow if I've got time. Maybe there's just a bunch of crud blocking something up somewheres, though I don't know that that would cause the problem. It will make it easier to see if it's leaking bright green stuff from around the head, rather than brown stuff I suppose.

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'77 Leyland Mini Van

After running the car to heat ( not too hot ) the system take the plug out of the back of the block ( don,t burn yourself ) then remove the radiator cap, if nothing comes out even after you use a piece of wire its blocked properly if you can get a flow you can at least give it a flush , ( use a bucket ) fill up with hot water from the tap and pour into radiator at least twice ( make a funnel from the top of a soft drink bottle it sits flush) , replace the plug and pour a bottle of brown vinegar in the radiator and top up with hot water , cap it and run the motor for a few minutes , repeat the flush then replace the plug, then using only water and rust inhibitor ( no coolant ) refill the radiator and start the car , as it comes up temp top up as required and take the car for a drive (at least an hour and take water with you ) , after you come back let the car cool enough to remove the radiator cap and start the car if you have bubbles then you have done a head gasket , if the level has dropped or it has dropped water as it sat you may have a hose leak , you may also have corrosion/ faulty thermostat in the housing ( better to have an 82 deg thermostat if replacement needed ) , if everything is hotter than normal but OK then dump some water and top up with coolant and move on to , running lean and/or timing slightly out causing you to run hot

my 2c

.

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