More helicoil possibly?

[Jonathan Webb]

My entertaining little 20hp marine diesel, takes 4 legs, two of which are on the block casting and the rear two are on the bell housing. I have now found that one of the pairs of holes has been well mullered in it's previous existence. I'm not sure if it is now too big (and possibly funnel-shaped) to take a sensibly-sized helicoil. The good hole is 10mm (10.3 at entrance) and the bad one is over 13mm at it's worst.

I came on here to to see if a helicoil would be strong enough for an engine mount - most applications seem to be in multi-bolt situations rather than a high-load application, and if is could be used with such a mangled hole?

I read this thread from October (https://www.mig-welding.co.uk/forum/threads/helicoils.86108/page-2) basically saying how great helicoils are.

I also read this thread where Devcon F2 and JB Weld were mentioned . Are JB Weld & Devcon similar products?
(https://www.mig-welding.co.uk/forum/threads/just-when-i-thought-i-had-cracked-it.89307/). I have JB Weld in stock - would that be up to it?

I've just had a quote from a local welder for £50 to fill it but I could buy a helicoil kit for less, so I've got the welding as a last resort and tbh, could do with not spending unless really necessary.

Any thoughts?
Thanks.

 

[PhillipM]

A properly installed helicoil will be stronger than the original thread was. But it depends what thread size you need to get back down to as that looks too large to make up with a normal helicoil if the good one is M10

 

[Ed ke6bnl]

check into thread sert solid thread replacement

 

[Rannsachair]

Your oversize hole looks way too big to use a M10 size helicoil or a timesert

See https://www.thorintl.com/Drill-Sizes-HeliCoils-Metric.shtmll or https://www.wurth.ie/media/downloads/pdf/short_form_catalogues/Timesert.pdf

Can you go up to say M14? or make your own threaded insert M14 od and M10 id then loctite into place?

 

[Wildefalcon]

Or try "big serts", I'd a similar problem with a rocker bolt hole.

Worked fine.

 

[Rannsachair]

Or try "big serts", I'd a similar problem with a rocker bolt hole.

Worked fine.

They look good though M10 x 1.5 drill size is 12.3mm, so still likely a bit too small.... http://www.timesert.com/html/engineeringdataBS.html

 

[MetalMonkey]

Try EZ-LOK - think they have a better range of sizes and less faffing about than timesert. No special tools required.

I've used them to replace knackered manifold helicoils on heads - handy as they are slightly bigger so you can get away with the same bolt providing there is enough meat left on the casting. I'm not keen on helicoils personally, maybe they weren't installed well but I've seen far too many fail.

https://www.ezlok.com/threaded-inserts-for-metal

 

[8ob]

Have you considered taping it out and just fitting stepped studs ? A bit cheaper than a helicoil kit.

Bob

 

[Jonathan Webb]

Have you considered taping it out and just fitting stepped studs ? A bit cheaper than a helicoil kit.

I haven't got any taps so would need to buy. It may be worth buying one or two. I couldn't find much in the way of stepped/reducing studs though. Have you got any useful leads? Tanks.

 

[8ob]

I haven't got any taps so would need to buy. It may be worth buying one or two. I couldn't find much in the way of stepped/reducing studs though. Have you got any useful leads? Tanks.

https://www.raceways.co.uk/conversion_wheel_hub_stud_14mm_to_12mm_1.5.htm

 

[Jonathan Webb]

Thanks, been going through your replies.
EZlock & Bigserts & Devcon are more expensive than getting it welded from what I've seen.

I've seen these inserts, which include a M14 to M10 offering: https://shop4fasteners.co.uk/fasteners/threaded-inserts.html, or these? https://www.ebay.co.uk/itm/Slotted-...19f12aae:m:m55h6y5LohUpp5jF5tZvEJQ:rk:26:pf:0 which might work if I drilled it to 14mm & Loctited in?

Or I could potentially put a bolt through from the inside and JB Weld the head it to make it captive and to pack out the enlarged hole & redrill at 10mm? For some reason, the engines I've encountered have the legs attached with bolts rather than studs, so not sure if I want to try this approach.

Or I could just go up to M14, but would prefer to keep the fasteners the same size. Probably.

 

[Jonathan Webb]

https://www.raceways.co.uk/conversion_wheel_hub_stud_14mm_to_12mm_1.5.htm

Thanks but I need another 20mm or so after the 14mm section. Also, I coudn't find anything that went from 14 to 10, which is fair enough as it's a big difference.

 

[8ob]

Thanks but I need another 20mm or so after the 14mm section. Also, I coudn't find anything that went from 14 to 10, which is fair enough as it's a big difference.

There are plenty of very helpful folk on here that will turn 14-10mm studs up for you Jonathan, you only need to ask, Help is what this place is about

Bob

 

[waldershelf]

For me option 1# would be drill and tap with a larger size and then go with stepped studs or just larger bolts. Option two would be drill out and fit one of the rethreading options, timesert, helicoil etc there are lots of options. I wouldn't go for the weld it up and re tap it unless there are no other options, similarly with JB weld, not sure I'd trust it in a high load application if there are other options.

 

[knighty]

what does the engine mount look like?

can you not bolt it on and stick nuts on the back? can't see in photos how much clearance you have inside

 

[RichardM]

as above but thinking a tapped piece of plate or nuts welded to a piece of plate to spread the load evenly

 

[Jonathan Webb]

what does the engine mount look like?

can you not bolt it on and stick nuts on the back? can't see in photos how much clearance you have inside

I've yet to make the mounts, but I'm hoping it will be nothing more than some 10mm unequal angle like this diagram (for amusement value

that piece of angle, item 2, is £80!)
I did have a quick look and I think theres a fair bit of space between the casting and the ring gear, so that is a possibility.
FWIW, the engine weighs 100kg and is a smooth (for its type) diesel. And driving a prop, won't have the torque grab that a car experiences when drive is taken up.

 

[Jonathan Webb]

as above but thinking a tapped piece of plate or nuts welded to a piece of plate to spread the load evenly

Hmmm. That has a certain appeal.

 

[Jonathan Webb]

Whilst I broadly understand tapping, I've never done it and not sure of the sizes of bits and threads.

Tapping it at 14mm: I managed to find a chart that wasn't American and it stated 14x2 and that requires a 12mm bit. Is that what you'd expect?

I've also read about taper & plug taps. As I can run this all the way through, I feel that a taper tap would be best for me as a noob?

Anything else I need to know?

Additionally, I need to buy new fasteners for the (non-SAE) bell housing. Is there anything special that I need to know about these. IIRC there are M8 & M10

Finally, following Bob's post, would anyone be prepared to turn me an M14 to M10 stud soonish? It would need to be: an M14 section ca 30mm long and the M10 section ca 25(? needs to allow for 13mm bracket thickness, and whatever convention dictates for the washer, nut and a bit of spare at the end). Please pm me with price.
Many thanks for your help.

 

[angellonewolf]

For the 50 quid is just welded or welded and taped ? If the whole job sounds good to me after all it's an engine mount you would not want to to brake ?