Defender T seal 300tdi

[Shortshank]

Hi, my apologies if I’m going over old ground. I’ve read lots of helpful posts about replacing T seals in the 300tdi engine but I am having a problem removing the actual No5 bearing cap to renew the seals. I’ve removed the bolts but cannot shift the cap (I’m working from underneath with the engine and gearbox in situ). Engine has done only 40k since a complete rebuild (previous owner thank you Series Kid) but I’ve had a persistent oil leak with all the characteristics of either T seals, rear main seal (don’t think so as the bellhousing wade hole is dry) or sump pan seal. On removing the sump I can see that one of the T seals is slightly recessed so could be the cause? Any hints on dislodging the bearing cap would be much appreciated, thanks.

[workingonit]

I am having a problem removing the actual No5 bearing cap to renew the seals.

The slight gap on the t-seal could be a cause, but if the sump was installed with sufficient goo then it should have filled the gap.

The crank seal supporting aluminium frame may have been sealed with self vulcanising rubber, which sticks to the 'back' of the bearing cap as part of the sealing process. Careful prying should break the seal. When you reinstall the cap you will need to scrape the old rubber and apply new. Sometimes a gasket is used instead of rubber when a new cranks seal is installed.

There are rubber and cork t-seals. Guiding the cap in without stretching the seals can be problematic. I try a more sideways installation rather that vertical.

There are a couple of alternatives to replacing old t-seals with new. I re-installed the cap (making sure I had re-sealed the crank seal); then I proceeded to push rubber soaked cordage into the 't', then the upright; let it set then trimmed it; don't know if it has been successful because I've got leaks elsewhere to resolve! Less likely to be accessible to us DIY is high pressure injection of silicon.

The manual says new cap bolts are required, but I could not find a supplier with the correct length. I don't think they are torqued to yield. Rang a well known independent workshop who said they always reuse the bolts, but on another occasion I got mixed results on whether to lube a new crank seal or not, so even a good shop might not have everything down pat; and if you do go there then don't lube a new crank seal.

A good source of engine oil leaking is the small o-ring under the cap that holds in a wax thermostat, located near the spin on oil filter (if your defender tdi300 is anything like the D1). This leak could be fooling you that you have a t-seal leak because you can't find the source of the leak anywhere else. The o-ring is very thin, and using anything else thicker will result in breaking the aluminium cap. The old seal will look triangular in cross section due to pressure of sitting in a tapered hole for years.

[jboot51]

the recessed t seal is probably not a problem as the sump gasket/sealant will cover it.
I put a slightly longer bolt into the threaded hole (sump bolt) in the rear main cap and use a pry bar to the outside edge of the block.
Instead of t seals, I use permatex ultra black, but allow at least 24hrs to cure. Use the same for the sump.

You might run into trouble with the rear main seal, silicone or gasket, it is going to be disturbed and will most likely leak.