Removing waterpump housing bolt 40+

[Shearwater]

I'm trying to remove the gearbox from a 40+ . The outer bolt on top of the waterpump was easy to unscrew, but the one between the drive shaft casing and the exhaust refuses to cooperate. I tried it with heating the gearbox where the thread is several times, loads of WD40, hitting it with an impact screwdriver many times (broke three bits) but it doesn't come loose. Any suggestions what I could try next? Or is is it now a matter of drilling out the head of the bolt?

[Adrian Dale]

If after heating (lots of heat) you still cant remove the bolt, your next step should be to cut the bolt through the jointing plate. Carefully cut through the fibre plat and bolt shank then split the casing.

Drill out the cut screw shank.... But, before drilling, make a steel pattern with precisely drilled holes; use a good piece of tensile steel about 1/2" thick. The hole that is to align with the good clear tapped hole from which you have removed the bolt should be drilled to a tight clearance fit for a 1/4 bsf bolt; the other, through which you will drill, needs to be the thread minimum dimeter. Clamp the gig onto the gearbox using the remaining tapped hole. Mount on a pedestal drill (don't try this with a hand drill) and carefully align then drill through the jig. The drill will follow the gig and stay true through the cutting of the bolt. After complete remove the jig and tap out the threads remaining in the drilled hole.

Remember before drilling out any bolt make a gig or the drill will run out into the softer surrounding material

Hope you get the idea I thought I have a photo but sadly not

AJ

[Collector Inspector]

OR

As Adrian says is cool but if you pick out the fiber gasket, cut the fastener as far away from the gearbox as possible and then have the gearbox in your hand you can:

Use some heat and a pin punch to drive out the fastener from underneath the pump housing. Clean up the original hole for new fastener.

You are then left with the remaining thread sticking up from the gearbox. Easy to access now when mounted in a vice.

Treat it like a broken stud.......as that is now what it is aye.

The chance is that the head and shank of the fastener being corroded and as one with the pump housing is your stumbling block.

Your preference either way will get the result.

Cheers

B

[Shearwater]

Thanks, these are clear instructions. I ordered few new bits and will try once more the impact driver after another good heating. If that still doesn't work I will follow the directions given.

[headdownarseup]

Heat.
PLENTY OF IT, always works for me with a good fitting impact driver.
I've never had one that i can't seperate yet.
I do however have the luxury of having oxy-acetylene cutting equipment at work which helps.


Cutting through the jointing gasket takes a while (but will work eventually) and as Bruce has mentioned, once the 2 halves are seperated, treat as a broken stud. How you remove this broken stud is up to you. (i'd opt for more heat and vice-grip pliers if there is enough broken stud protruding above, dont be scared of lots of heat)

Jon

[Shearwater]

What is actually best: heating the aluminium of the gearbox around the bolt of the bolt itself by applying heat to the head of the bolt and by conduction the threaded part bolt itself? I would say heating up the aluminium casting would be more effective because the aluminium expands more than steel and is heated up faster than the steel bolt inside. Correct me if I'm wrong.

[Nudge]

I heat up the bolt so it is red hot... The bolt expands breaking the seal of corrosion. It takes a bit to melt the aluminium in open air. If your concerned about the aluminium melting put some wet clay around the area, it works like a heat sink.

[Charles uk]

This method only works with the compressed fibre gasket.

The screw/bolt between the exhaust & drive shaft is very rarely locked on the thread end, more often than not is locked around the parallel part & the head where it goes through the water pump housing.

So you need to remove the gasket, I've shredded these where people have used hermetite to stick them in place with a jigsaw blade that I'd ground all the teeth that would damage the aluminium on the pump housing & the lower unit, & just remove the guts from the gasket, when they're just squeezed in there a sharp electrical screwdriver will chisel them to bits.

Then remove the drive shaft tube pinch bolt & replace from the wrong side with a coin in the center slot, tighten the bolt onto the coin the put enough pressure onto it so it starts to release it's grip on the drive shaft then with a small rubber hammer drive the pump housing towards the lower unit, lever it back into place & drive down again several times, this will break the aluminium oxide bond between the screw & the pump housing, apply penetrating oil & unscrew.

[headdownarseup]

Heat the bolt first, then quench with either wd40 or diesel or similar, then heat again. The aluminium will expand quicker than steel so giving you a better chance at removing what's left of the steel screw.
While the bolt/aluminium is still hot/warm, use a pair of vice grip pliers to turn what is left protruding above.Alternatively, if you have some to hand, a stud extractor provided there is enough for it to grab hold of?

Either way, heat and lots of it before anything else.

If this fails, then i would drill out and re-tap using A-J's jig method.

Jon