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300TDi "P" Gasket


Boydie

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Any clues on how to get this little sucker to seal ? (It's a definite design revision for my engine rebuild topic, possibly with an inserted "O" ring, but I digress) Using the tin gasket, I've tried now four times and after a few hundred kilometres I still get a tiny weep, losing around a spoon full of coolant in 1000 kilometers I'd guess. Not disastrous and life or engine threatening but annoying because it should seal and be totally water tight :rtfm:

Has anyone tried using a gasket made from the old style gasket paper with any sucsess ? and if so what was the material they used, it's thickness and make.

The metal LR one just doesnt seem to want to seal. I even had the thermostat /alternator bracket body skimmed to ensure that it was totally flat (there were a few etched areas on the face that mates to the block that might have been a cause for leakage) and had the original threaded tappings in the block replaced with helicoils to that I could increase the torque on the three long retaining bolts. I've tried with the gasket dry (twice) with silicon (once) and Rolls Royce jointing compound, all to no avail so .............. any suggestions ?

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Have you tried putting a little bit of grease on it when you put it in? Or are you doing the nuts up to the right torque setting?

Try using something like engine degreaser or carb cleaner and make sure the surfaces that contact the P gasket are thoroughly clean. I am not an expert but hope this helps.

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So far I can honestly say I've tried all the things you have advised, excepting using grease, currently I have a new gasket with RTV silicon drying in the groove to allow it to go "solid' before i install it. I'm not a fan of metal gaskets and my experience with teh so called new cylinder head gaskets is dismal, whereas the composite one currently on the 300Tdi has done in excess of 150,000 kilometers without any problems, the multi-plate metal units didnt last 70,000 ! so I think a return to a "paper' gasket to replace the works metal "P" gasket may well be on the cards, the one huge advantage of the composite "paper" gaskets is/was that they swelled up when in contact with coolant and thus were, to an extent, self sealing.

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I think its possible for the aluminium to corrode in this location become thin and not seal properly. You may want to check the condition of your engine parts. How long are you leaving the rtv silicon before you assemble it? You don't want it going too hard before you put the pieces together.

Jad

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Jad, you're right about corrosion however I can honestly say that the engine has never ever had anything less than 25% mix of coolant in it and the waterways are clear, so there is very little corrosion.(unlike the photos in the forum link on this subject!!).

There was a slight trace of oxidisation, and we are talking microns here, even so I had the pump housing skimmed at the engine shop, they only took .002" off it to bring it back to pefect and as new and even then only off the rear face that comes in contact with the face of the block. The face opf the block itself is good and you can still see the original machining/milling marks, I painted it with engine blue and drew a straight edge over it and confirmed that it is true and flat. The original three bolt tappings were a little slack so I tapped out them out and replaced them with helicoils, none of the tappings extend into the block waterway and I am able to apply greater torque on these three bolts as a result.

I still get a tiny weep on the external face near the engine dip stick, possibly because this is the narrowest face and if its to leak it would be here or on the top, the inner face has more surface around the connection to the block. If that doesnt make any sense you will need to look at the actual face of the housing.

The amount of RTV silicon is only the tiny amount that it takes to fill the groove in the pressed metal "P" gasket, in short giving it a "fitted" O ring that should easlity compress and (hopefully) seal, - very similar to the sealing rings on the composite cylinder head gaskets - if this adaptation of the works gasket is not successful the next step will be a return to a hand made composite gasket.

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Did my water pump and P gasket last weekend...Cleaned the face on the block and stuck the gasket one with Blue Hylomar ...Mounted the water pump housing quickly then inserted a new long bolt through the housing/P gasket and refitted housing bolts/water pump etc no leaks at all....quite an easy job really....Letf it all over night to settle before refilling the coolant and been fine since

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Point taken I will try again ............... if at first you dont sucseed ,,,,,,,,,,,,,,, a bit like Richard 3rd, 500 years to get out of a bloody car park, you gotta keep trying ....... he may have as well lived in Sydney :rofl: poor bugger never had a chance with only 1 HP

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I did the "P" on the black disco before it got sold and when I found the steel shim it went in the bin... and a traditional paper type with silicone when in its place, A friend has the truck, so I'll know if it fails!... i'll be keeping an eye on it. I don't like the idea of the steel shim, and I can't see why they'd use it over a traditional gasket.

I've got the Camel to do next and that will be getting the same treatment.

Mav

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  • 2 weeks later...

The early 300Tdi P gaskets were of paper and tended to blow out a section with disastrous results for the engine. There was a Doctor in Pretoria who took LR to court over this piece of bad design and won. Long time ago now.

The metal/plastic P gaskets do tend to weep and leak a bit (I have changed mine twice now) but they do not blow out altogether.

The problem, of course, is that cast iron and aluminium alloy expand at different rates.

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Same as "Muddy" I just changed the water pump & 'P' gasket on mine & used blue Hylomar not done more than 300 miles since but no leaks so far who ever had changed the previous pump had used that horrible orange instant gasket without a gasket at all & it leaked like an old kettle

Jim

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Jim, (both of you) The Bestobel high temperature water gasket material I obtained (a 500mm x 500mm x 3mm thick sheet) has a very fine copper mesh woven through it, while this made it difficult to cut with sharp wad punches and snips I guess it will prevent the "blow-out" you mentioned, I guess if its good enough for high temp high pressure pipe and flange gaskets it will be okay for the LR 300TDi water pump, anyway, so far so good and no more leaks ^_^

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