Club 80-90 Forums

This one is interesting.

I have recently had the engine out so in turn have changed a few things.

My problem is that the oil drain plug is actually a broken off spark plug!!

I have ordered one from just campers but this is about half the diameter
it needs to be for my engine, a 1987 1.9 DG.

The spark plug will not fully tighten so I have an oil leak!!

Does anyone have any ideas how Ican fix it?

LIDDERS

Spark plug trick is an old, get-you-going mod, seen it on a few motors. If it` won`t tighten up, then either the spark plug thread is stripped (unlikely) or the sump thread is stripped (likely)

Will need to either get the sump helicoiled so a 14mm size sump-plug will fit it OK (the best way), or if there`s anything to play with maybe have it tapped out to the next size and try and get a sump-plug to suit (not the best way) Luckily spark-plug sized helicoils are common due to people stripping plugs out of cylinder heads all the time.

If you`re not familiar with helicoil kits, then you`ll need either an engineer or a motor-engineer to sort it out, and that may well mean dropping the sump to do it. Try a local (yellow Pages) cylinder head specialist or similar.

My problem is that the oil drain plug is actually a broken off spark plug!!

so is mine, I put on a new sump plug washer and simply put the half a spark plug back taking the approach if it aint broke dont fix it approach.

The thread pitch (number of threads per inch "in old money") is different for the normal VW sump plug compared with the threads on a spark plug. Both are 14mm diameter.

If you are going to have it helicoiled for the proper sump plug it can't be the same as a spark plug helicoil.

Hope this helps

1st time i came to change the oil on mine, found that the sump plug was held in with body filler nice!
i bought a U.N.F. taper tap, think it was 9/16'' but will check at work today, the tapping drill size was same as the stripped out hole size, tapped it VERY carefully keeping the tap square on, used a short cap head bolt as a sump plug & copper washer til i could make a proper one at work, but in reality, the caphead is fine.

This is is tip that an old car mechanic gave me.

If you are retapping a hole into an engine and you are worried about the swarf from the tap going into the engine fill the flutes of the tap with grease, this will then hold the swarf.

agreed, grease ya tap flutes! it was 5/8'' U.N.C. i used, a very similar thread pitch to the metric original sump plug, 14.5mm tapping drill recommended size , but the stripped hole was about 14mm so i just tapped straight in, unfortunately the sump cant be unbolted to do the job on the bench, but with care it is possible with the engine in.

Sorry . . . 5/8'' U.N.F. not U.N.C.

thanks for this I will try the new seal ring then any of the others as a 14mm kit is over £50!!!!!!!!

I had to spend £25 on one for the exhausts bolts.

LIDDERS

Just tap it to M16 and use a Renault sump plug.
Pour engine oil without the sump plug in and flush out the swarf.

Simon Baxter wrote:Just tap it to M16 and use a Renault sump plug.
Pour engine oil without the sump plug in and flush out the swarf.

I am shocked at you suggesting using a part from our neighbours

Neoprene sump washers as used by Ford I think, can be quite useful in these situations, taking up a bit of inaccuracy in the hole alignment or plug threads if it weeps.

Simon should I go to the "DARK SIDE".

What thread would this be?

I'm liking the idea as a complete fix!

LIDDERS

worth checking E-Bay for a tap, whether you go for the renault bolt and M16 thread, [this will probably be a fine pitch thread, not standard M16] or what i used, 5/8'' U.N.F. and a short 5/8'' U.N.F. caphead bolt. make sure you go for a taper tap tho, as you stand more chance of sucess than a second, or plug tap which have little or no lead angle ground onto them.good luck with it!

Most taps seem to be seconds rather than 3rd or taper taps, that are in sets such as this...

Wiki - Tap and die sets

With the correct tapping drill they can usually be started OK, after two or three goes, just keep it straight and the force be with you...

Wiki - Tapping drill sizes and thread pitches