Need help with engine cooling question

[Peter B]

Dear all, the other day when checking the water level in my Lehman 120 (1975 era), I noticed the centre of the cap showed some corrosion. I had a bit of trouble re-seating it, and when I took it off again to check the alignment, there was a 'ping' and the whole pressure cap part leap apart and went to the 4 corners of the ER. Ie it is cactus…but it has done pretty well I think it's the original cap. I expect (hope) I will not have too much trouble obtaining another, but I have looked on vain through the detailed manual I have, and the radiator cap is listed as part 2C302, in the diagram as no 5, but nowhere does it mention the relief pressure - which I would think the relevant thing to know in sourcing a new alternative, as the factory part will no longer be available.
Anyone know for sure..? Most cars are about 10-14psi I think from memory, but would this be the same. The manual says optimum temp range 79-88C, or ~190F and that's where she sits normally, but I'd rather not do a trial and error thing...

 

[BruceK]

Pete, I`m sure the expansion tank cap is 4psi. For a modified filler neck, cap psi rose to a dizzying 6 or 8. This from memory, but I`m sure I found it in print, before ordering new caps from AD. You may have trouble finding a 4 psi cap,I did. Cap sizes vary, take your fragments to your automotive supplier and see.The part number is correct per my parts list.
A major plus of new caps, coolant overflow loss markedly diminished. The old one may not have been sealing for a long time.

 

[Peter B]

Thanks Bruce. Gives me an idea what to aim for. I would have expected a higher pressure. I wonder if now might be the time to see if I can even get the neck insert and adapted cap which allows a siphon return tank arrangement. I know Marin got two - which at last we heard he had not got around to installing, actually.

 

[Bay Pelican]

Pete

Call Brian at American Diesel on the American East Coast (EDT) and ask him for the details on the cap. American Diesel are Lehman experts. It may or may not be worthwhile for you to have him send you a cap. If you are uncomfortable because it is unlikely you will buy from him tell him a couple of his customers recommended him for advice. You can mention Bay Pelican if you wish. Phone US: 804 435 3107.

 

[Peter B]

Thanks Marty, if I get stuck, I might just do that. First I'll try the Sydney based Lehman parts place if no-one locally has the item. I was just hoping someone might know the pressure setting off the top of their head. Bruce may well be right...
If so, then our local Repco shop may well have one which will fit the bill. If not...I feel a wait coming on.

 

[BruceK]

Peter, Found my order sent to AD and their dispatch slip, definitely 4psi caps, their part ref 822-0302. My local Repco shop shook their heads at 4 psi. I`m sure AD sells filler neck conversions, not seen one, maybe offsets the neck to give clearance from above.
I`ve never found the Sydney Lehman parts source,(?Jos Bots), I`d appreciate any details. AD are helpful and quick, use USPS to deliver, 10-14 days. I enquire/order by email but fax them my cc.

 

[Peter B]

Wow, I'm impressed. I saw Bob Smith's email address in and ad for American Diesel in a 4 yr old Passagemaker I was glancing thru last night before retiring it to the surgery magazine pile, and saw Bob's email address in the ad. I shot off a query, on speck as it were, and received a reply this morning, advising the best idea was to go the adaptor neck and cap for the siphon/reservoir arrangement, and a quote for costs, which were quite conservative. It has motivated me to go that way, as the parts are so small, and can be posted. I'll get the reservoir here, as they are a basic auto part. Hopefully, problem solved. Thanks all for the input.

Bruce, the contact I have for the Sydney Lehman supplier is
0418 427 474. Can't remember his name, but he did come through with the new heat exchangers, and exhaust injection knuckle I had to have replaced about 4-5 yrs ago. He used to/may still have, have an ad in the Trade-a-boat mag, but the PO also advised me of his being a good resource for parts in Oz.

 

[Tom.B]

The "all-mod" thread! ;-) nice

 

[Peter B]

Yeah….guess radiator caps are not that sexy a subject, eh..? :lol:

 

[CPseudonym]

Radiator caps are about the most perplexing mechanical item we moderators can wrap our minds around