Oil and transmission oil ger plugs?

[WolfRichter]

Hey there R4 folks. I have a little leak by the tranny and engine oil plugs of my '85 R4 850cc B1B respectively. I have tightened both a bit but I have always been curious about their shape. Surely there are bolts with shoulders around that I could use a crush washer on? Does anybody have experience with that and could tell me what size to use? Thank you all in advance.

 

[jjad]

I don't know about the transmission plug, but the engine sump plug should have a 16mm crush washer.

See https://www.renault4.co.uk/forum/threads/chugging.10606/post-73528

 

[angel]

845cc engines have M18x1.5 thread plugs. Coincidentally, it's the same thread size used on oxygen sensors, and there are always shouldered plugs available at exhaust shops.
Both gearbox plugs are tapered and seal by interference fit of their threads. There is no machined boss on the gearbox, so it's impossible to use a plug with a crush washer there. If you see drops of oil at the gearbox drain plug, it could well be a leak from another point - usually the driveshaft oil seals and bearing carrier O-rings - that trickles down to the drain plug, as it's the gearbox lowest point.

 

[jcarruthers2]

Hi

The sump plug is prone to leaking even with a sump plug which is in good condition and a new washer. I wrap plumbers tape around the thread which works a treat when I do an engine oil change.

As the sump plug and gearbox drain plug are in close proximity, it is sometimes hard to tell whether you are losing gear oil or engine oil. Engine oil has a very different smell to gear oil, I smear a little on my finger from where it is collecting on the underside of the car and sniff it to work out whether it is gear oil or engine oil. If the leaks are not coming from the actual drain plugs, common gearbox culprits as Angel mentions are the diff oil seals and O rings. Common engine oil leaks in that area can be due to the sump gasket itself, the semi circular sump end gasket or the crankshaft oil seal.

 

[Cyprusnoddycar]

I think it's always worth fitting new 'magnetic' sump/gearbox plugs on R4's using plumbers PTFE tape with new copper washers.