6 replies to this topic

[DClarke1954]

In "fixing" the lack of a thermostat yesterday an opportunity presented itself to also install a heater on/off valve instead of the "straight thru" pipe that was on there.

Unfortunately the garage that installed this "new" head for the previous owner has used odd and incorrect bolts and damaged the threading in the head.

The front fixing seems pretty much ok and I can get a 1/4" UNF to get a decent purchase.

The rear fixing is an entirely different case, you can push a 1/4" UNF bolt all the way in and pull it out again without bothering to turn it at all.

If I use some spare (and overly long) bolts and nuts to see how deep the holes in the head are then it seems that both holes are drilled to the same depth but one has lost all its threading.

 

What options are there to remedy this?

1. Try and drill the failed hole out in-situ and attempt to put a helicoil insert in there?  - Sounds awkward in-situ.
2. Clean, flush the hole out and chemically bond a split-tailed 1/4" UNF stud into the existing hole and hope it does not pull out.
3. What else can I do?

I can't be the first person to pick up someone elses "bodge" to a head, can I, so what is the standard approach to fixing this?

 

Many thanks in advance.

 

Dan.

 

 

 

 

[stoneface]

Personally, I'd either helicoil it or tap it to the next convenient size and make a reducing stud from whatever the new thread is to 1/4" UNF

 

 

[Ethel]

If you're not tooled up to helicoil, you've nothing to lose in trying to glue it in. Every chance it'll hold well enough & if it doesn't you'll only be back where you are now.

[Shooter63]

Personally I would helicoil it, the smaller kits come with the right size drill for under £20.00. The amount of metal removed is minimal, so it should be an easy job, grease the drill bit to hold the swarf.

Shooter

[DClarke1954]

Thanks everyone,

I have ordered stuff to cover all options.

Hopefully none of the options/possibilities will preclude another, I just have to decide upon my plan of attack.

I have a 1/4" UNF helicoil kit arriving tomorrow, as well as a 5/16" drill & tap set and some 5/16 bolts.

I already have M8 metric drills & taps and that would only mean drilling out one hole on the heater valve flange.

I just wasn't sure what the "Normal/best" approach was considered to be.

 

So it might be (order of attempts):

5/16 drill & tap.

1/4" UNF helicoil  (I need to see the clearance size/tap of the helicoil).

M8 (last gasp option) I can make my own M8 stub to 1/4" 28tpi stud.

 

I really want this fixed so I can progress to a tune-up/rolling road session to resolve my performance issues. 

 

Thanks again for you advice and "been there, done that" wisdom.

 

Dan.

 

[Steam]

Helicoil first as that will be the smallest.

[Cooperman]

Helicoil first as that will be the smallest.

Yes, that’s what I would do, then it’s as intended.