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Sharp

Engine Oil leak(s) - where to start (300tdi)

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I'm finally going to tackle the oil leaks which are making a mess of the engine bay and wondered if anyone had any advice on where to start or some common culprits. 1998 300tdi 110 CSW. Few pictures...

P.S. for the smart Alecs, the oil caps off to remove the cover!

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I suspect you're trying to solve the impossible, but...

I would start by replacing the rocker cover gasket, and the breather down-pipe.  Mine split at the join with the rocker cover, and then so did the replacement, so I went to silicone hoses and they've held.

You may also find that's diesel around the injectors, most likely from the fuel return pipes.  They're quick and easy to replace too.

I'd wait for someone who knows stuff to comment on the larger leak near the exhaust manifold?!

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Just had very similar with my 300Tdi, check pipes to and from Cyclone Breather, check Cyclone Breather 0 ring and replace and most importantly check Dipstick is seated properly ie pushed in all the way! Mine wasn't and spewed oil all over the engine within a few days! Sounds daft but does happen.

Have cleaned mine down with a pump sprayer bottle, paraffin and using a small paint brush. Now nice and clean and still dry ;)

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99% sure your exhaust manifold gasket has cracked

Definitely check the leak off pipes. Remove them and fold 180 degrees to see any cracking

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Every 300tdi I have owned (over 20 of them over the years) has come to me with the original type intake / exhaust gasket split as mentioned above. They always split on the intake part causing the oily mess. I change the intake gasket, rocker gasket, leak off pipes and breather pipe on each 300tdi I have as a matter of course. Also check the injector pipes are tight as often found a loose one weeping very slightly.

Also the only way to get a truly leak free cyclonic breather is to fit an Allisport one - I’ve changed o rings and tried additional sealer on them plenty of times in the past but the plastic always distorts when bolted up and they start leaking again. Only since I have fitted an Allisport breather a year or two ago has my 300tdi top end been absolutely leak free.

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Thanks for everyone's replies, there's loads to go on there. Exhaust manifold gasket, cyclone breather, rocker cover gasket, fuel return lines, oil breather pipe and the dipstick. I've got a week off next week with the intention of stripping the inside out, sealing a few leaks and insulating so will hopefully have a bit of time to clean the engine bay up and see how it goes from there. I'll try the o-ring for the cyclone breather and hopefully that at least stems the flow to something a bit more reasonable!

Thanks

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Might be worth cleaning the engine thoroughly, then do one of the fixes and take it for a spin. Come back and check, if the engine is still clean and dry you got the problem solved 1st time ;) if not hopefully you will see where the oil is blowing from and that will give you an idea what to look at next.

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Is there a new manifold gasket design? I have just replaced mine but it came as one piece not separate inlet and exhaust.

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The originals were fibre type which I always found split, the replacement type now I think are metal composite? It’s a few years since I’ve had a 300tdi now.

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I ordered a bearmach one this morning and it looked like it had metal sections at either end

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Yes ok I see what you mean. That's what the one I've fitted looks like. 😀

Here's my leaky gasket and the new Elring one.

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I'm de- leaking a 300 Tdi this weekend and this one is coming out as rear main is leaking and front inner crank seal too . In addition it's leaking around the cyclone , breather pipe connections to engine , rocker cover , oil cooler pipes , forward breather plate to crankcase , vac pump to block and around vac pump outer plate/body joint , I'll be dropping the sump and the oil filter housing too just for the hell of it , no stone unturned and all that , it will be good to have it dry when it leaves .......well apart from the PAS pump & pipes but that will be done  in a few months as it still works ok and this session includes a new clutch and timing belt  .

The simple and common causes are cyclone / rocker cover / breather pipes / manifold gasket  as already said above .

cheers

Steve b

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Just an update on this in case it helps anyone, it's pretty much been a success and 5 months on the engines still looking pretty clean although I still have a very slight weep from the exhaust manifold gasket. This was the old one:

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It was quite an easy job and I followed the instructions from this - https://youtu.be/kB5onEGqm7c. It was quite a mess and I spent a lot of time cleaning out the holes and cleaning up the surface with a stanley knife blade, brake cleaner and scotch brite.

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I forgot to resize my images and even though I've deleted the big files it's not letting me upload anymore so I'll post the rest again.

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The bolts that came with the new kit were all oval shaped, I'm not sure if they're meant to be like this but I put the old ones back on anyway:

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I cleaned the inlet out with petrol and then washed it out with water and left it to dry off with a hair dryer pointed down it till it was dried and didn't smell of petrol anymore

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There was a film of something on the new gasket, I'm not sure if this should have been scrubbed off but I left it on

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All cleaned up and reassembling

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I took the cyclone breather out and cleaned it up with petrol along with the pipes that were on it. I replaced the oil breather down pipe as well

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I had bought a new rocker cover gasket and washers but I thought I'd run it a while before fitting it. The old one was nicely seated in and if it wasn't leaking from there I didn't want to disturb it too much. As it turned out it's not leaked from there so I'm glad I didn't mess around too much. I thought I had ordered a new O ring for the cyclone breather but I can't see that I've ordered it. I think I used one from an assorted box of orings and if i remember correctly it was a little thicker and made the breather a bit harder to put back on but it seems to have sealed it. The parts were these:

exhaust manifold kit - ERR3785

breather pipe - the code on my order was LLH500170, I think the correct code is ERR3084

rocker cover gasket that i didn't fit - ERR2409

This is the box of o-rings I replaced the cyclone breather o-ring with, probably from amazon or ebay. I have a few different assorted boxes, although more often than not you find you have every size apart from the one you need!

image.png.05e99ad3c38ad1bf44afbb8d0372a52e.png

 

Edited by Sharp

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The new nuts are meant to be slightly deformed, when tightened up & torqued the nut grips on the stud thread.

crankcase breather O ring seal part number is LLO100000

Quote

breather pipe - the code on my order was LLH500170, I think the correct code is ERR3084

The 9 digit number is the latest updated number.

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