Farmall Cub

Bad news from Andy here in the UK.

Slight weeping of water from the cylinder head on my 'restored' '48 Cub is of some concern! This includes slight bubbling around one or two spark plugs. Symptoms dissipate once the old girl is nice 'n hot - presumably as things expand and take up the slack.

I've tried dosing with Bars Leaks (a trusty liquid remedy available here) but with limited success.

Guess I know what the response will be - but make my day and tell me there is an alternative to purchasing a new cylinder head.

Thanks in advance as always for any help.

By the way my last trip to France to acquire a second '48 Cub with plow and cultivator was fruitless - heap of junk - but I did retrieve the cultivator. Photos can be deceptive - lesson learnt the hard way. Should have listened to Mrs Mac!

Andy

Try retorqing the head

Was cylinder head recently removed? Head bolts require a sealant applied to threads to keep coolant from seeping past the head bolts.

Get engine hot to evaporate accumulated coolant. Shut off engine, sprinkle flour (baking type) on head. Watch the flour for indications of coolant source. I would remove the hood to get a closer look for the source of the seep.

If retorquing the head bolts doesn't solve it and you find the source of the leak (i.e. gap in head gasket), you may not need a new head, just to re-deck (rather, surface plane) the existing head to flatten it out. A machine shop will be able to do this for you. Then you would need a new head gasket, sealant applied to the gasket and the head bolt threads (as Eugene stated above).

Wish you the best!

You might want to check outlet net on head also it may need to be surfaced to.
Coolant may be leaking from that location and getting into sparkplug holes and running down front of head and wicking along gasket making it look as if the head is seeping,Had one do this .
Just a thought

coolant bubbling around spark plugs may indicate possibly it is leaking down around them from above, such as a radiator hose or outlet neck, and plug is not sealing good so it is getting a little hot gas leakage.

I have had trouble with leaking head gaskets on a 6 cylinder motor I rebuilt once. On the third head gasket replacment I used a copper spray to aide in sealing the gasket. That took care of the problem. So as an added insurance I would recommend spraying the head gasked with permatex copper sealer.

spgeid, many years ago before there was Copper Coat we used grease from a grease gun on the head gaskets, but Copper Coat works better and is less messy. I use it on manifold gaskets too.

Thanks very much for the helpful input. I will try the various remedies when time allows.

My concern is that it looks as though there may be water seeping through the casting on the top of the head which suggests to me corrosion and breaching of the water jacket. Hence the fear a new cylinder head may be required.

Anyone experienced this?

Andy

There is a water jacket in the head, that is sometimes damaged by freezing. I have never heard of a flat head allowing water to seep through the casting, that is quite a thickness, and would indicate quite a bit of porosity or damage. I truly suspect the water is coming from another source and collecting in the spark plug depressions. The fit of the radiator hose (top) on that filler neck is always a bit troublesome, and requires precision placement and tightening of the clamp.

I have seen a couple of heads that were cracked right where the water outlet bolts to the head. No sign of freezing anywhere, and the metal is pretty thin there. I have one laying in my scrap pile at present.

I agree with John that if it is bubbling around one or more spark plugs, those plugs may not be fully seated. These Cubs sometimes get hard to make the plug seat fully, due to carbon and corrosion. A thread chaser will help, if you don't mind the crap going into the cylinder....usually doesn't hurt, and will blow out next time you crank it.

Andy:

The head on Ellie was giving me fits. After the 2nd attempt at getting the weeping stopped, I finally saw the hairline crack between #1 and #2 spark plug. Found a used head in good condition on I think it was and that was that. Got a new head gasket, put the replacement head on ... end of weeping issue.

From what you describe that is exactly what I found. Sorry no better news to give .. but as they say .. that is the rest of the story ...

search results for a Farmall Cub Engine Head

Thanks Guys - yup I think Rudi has hit the nail on the head - water definitely seems to weeping through the casting which suggests cracks and corrosion. The top of the head also looks uneven as though it has been bodged with weld or filler then made pretty with paint - another lesson learnt the hard way.
Guess I'll have to bite the bullet and source a good replacement cylinder head. Trouble is postage to UK is near as dammit twice the price of the head! Have spoken to an agent in UK who can hopefully have one sent over from US with bulk order.
Do we know if new heads are produced in the US or in a back street in Beijing? Is it best to source a good original?
Thanks and will keep you posted. Andy

AndyMac wrote:Guess I'll have to bite the bullet and source a good replacement cylinder head. Trouble is postage to UK is near as dammit twice the price of the head!

For sale wanted section of this site. Several folks sell used Cub parts and ship overseas.