Club 80-90 Forums

Hi Guys, first post after joining the ranks with a 1987 1.9 Autohome Kameo. A few things need doing, but got an unexpected surprise during the oil change, the sump plug was fitted with two ptfe washers plus two crush washers, and had already been helicoiled. The Helicoil came out still attached to the plug. I tried a Renault M16 plug and leaked a couple of thimbles overnight cold.
It looks like who ever had fitted the Helicoil had not tapped completely through the sump thus leaving the space for all those washers. I'm not sure the job is square either and was wondering next best steps: should I get it tapped right through or start again drill out and retap for a larger Helicoil and reuse the Renault plug.

Has anyone gone with anything bigger than the usual M14 Helicoil for a T25?

Comments appreciated. Ta

Usual method is to drill out then tap an M16 thread.
If the hole is mullered then you can try temporary seal.

I'd be considering the services of a thread doctor, because you need to calculate / measure how much metal is left

M16 helicoil drill size is about 16.25mm which leaves very little flat to seal on but should be possible.
The M14 helicoil outer diameter is about 16.1mm so you should have enough metal but if it's bodged who knows.

kevtherev wrote:Usual method is to drill out then tap an M16 thread.
If the hole is mullered then you can use the bung method.

Can't tap M16 after M14 helicoil, not enough metal left, would need to be M16 Helicoil
M16 with no helicoil is 14.5 drill size
M14 helicoil outer diamerer is 16.1mm

There's an M17 repair kit on Amazon..but I fear that's a step too far

kevtherev wrote:There's an M17 repair kit on Amazon..but I fear that's a step too far

Where would you get an M17 sump plug to fit the recess?

I think M16 helicoil would work (Brickwerks do the M16 sump plug) but at these drill sizes and after a bodge easy to get it wrong and then you are lots of trouble, so I'd say use a professional in this case.

itchyfeet wrote:

kevtherev wrote:There's an M17 repair kit on Amazon..but I fear that's a step too far

Where would you get an M17 sump plug to fit the recess?

I think M16 helicoil would work (Brickwerks do the M16 sump plug) but at these drill sizes and after a bodge easy to get it wrong and then you are lots of trouble, so I'd say use a professional in this case.

Yeah it would take some re engineering to fit the hex head in the recess

.[/quote]

Can't tap M16 after M14 helicoil, not enough metal left, would need to be M16 Helicoil
M16 with no helicoil is 14.5 drill size
M14 helicoil outer diamerer is 16.1mm[/quote]

I guess that explains why the M16 Renault plug is ineffective!

I don't think there is anything to loose in running an M14 Helicoil tap through to the prescribed depth and retrying an M14 Helicoil and if that fails go the M16 route. This being last shot at the engine casing, any recommendations for a capable machine shop in the Exeter area?

Thanks to all for your ideas and comments, appreciated.

sump is only 10mm thick I find it hard to believe its not drilled and tapped deep enough.
The smallest helicoil readily available is 1D so 14mm deep, something is very wrong, perhaps the hole diameter was drilled too big.
Worth a try fitting a new M14x1.5 coil but be careful, I once lost my sump plug on the motorway, it wasn't something I'd like to repeat.

We tapped a mate's sump out to M16 and put an M16 x 12mm socket head capscrew in ... snug fit in the recess and just the job.

Ian.

How about using m16 x 1 special pitch tap , needs 15 mm bore.
Use a spiral tap to aid swarf to come out of the bore when tapping .

read above it's already been M14 helicoiled you can't tap M16 not enough metal

Never used one but been told they do work;

http://www.ebay.com/gds/How-to-fit-a-Un ... 940/g.html" onclick="window.open(this.href);return false;

It might work, but you'll never get that umbrella clip out again?!

For reference a Renault Traffic M16 sump plug, single crush washer and a splash of thread sealant is doing the trick.