exploding swirl pot

[jason1788]

Strewth! My swirl pot failed spectacularly at the weekend. The bottom looks loke someone has had a can opener on the seam, neatly slicing clean through around half the circumference. Anyone seen this before? Not sure if to try and get a new pot or the old one welded up.

[dodgyviper]

unlucky.

Go for a replacement - had a crack in mine and it took a NW dealer 3 attempts at welding before they gave up and put a new one in.

But then again - that could just have been the dealer - hope no other damage was done when it went

[john57]

Mine split big time about a year ago .... had it welded by Paul at Austec - been fine since.

[sjpalmer1]

I would check the small bore pipe that runs between the swirl pot and expansion tank. If it becomes blocked it can have dramatic concequencies.

[jason1788]

Mine is pre-serpentine so has no separate expansion tank. The only pipes in and out of the swirl pot are 38mm, so presumably no blockage there. I think it's just a fatigue failure that went whilst it was running hot and at pressure, presumably close to but not quite at the blow-off pressure of the filler cap.

[MickC]

My (serpentine) swirl pot went at the seam too. Had it welded twice, it still leaked as soon as it had heated up/under pressure, so got a new one.

[victormeldrew]

I can't help thinking these failures are somehow related to the reluctance of the brass cap to come undone, and the amount of torque that gets applied.

[jason1788]

It's the bottom seam that failed on mine. No torque is reacted through that. I could understand the mounting brackets cracking, but that's all. I am sure this is a fatigue failure caused by the flat end flexing slightly under the pressure.

[victormeldrew]

jason1788 said:

It's the bottom seam that failed on mine. No torque is reacted through that. I could understand the mounting brackets cracking, but that's all. I am sure this is a fatigue failure caused by the flat end flexing slightly under the pressure.

If the plug is seized, and tremendous torque is being applied to the brass screw with a crowbar to free it, what do you suppose is supplying the equal and opposite force to prevent the swirl pot from spinning?

[jason1788]

victormeldrew said:

.... what do you suppose is supplying the equal and opposite force to prevent the swirl pot from spinning?

The bracket that attaches it to the engine? Certainly not the seam at the bottom of the pot.

I should add that this is a pre-serpentine pot with the blue plastc filler/pressure relief cap on it, I believe the seams are different to the later type.

Edited by jason1788 on Thursday 10th August 15:41

[victormeldrew]

jason1788 said:

[quote=victormeldrew].... what do you suppose is supplying the equal and opposite force to prevent the swirl pot from spinning?

The bracket that attaches it to the engine? Certainly not the seam at the bottom of the pot.

I should add that this is a pre-serpentine pot with the blue plastc filler/pressure relief cap on it, I believe the seams are different to the later type.

Ah - mine is serp, and the tank is attached at the base (perhaps the mention of "brass plug" should have suggested that? ) with the seam being the join between base plate and tank. Apples and oranges.

Yes, I should have noticed "Mine is pre-serpentine so has no separate expansion tank" as well!

Edited by victormeldrew on Friday 11th August 09:57

[jason1788]

I'm getting it welded up next week. If the welding doesn't work I'll have to take a look at upgrading to separate swirl pot & expansion tank, presumably it must be a step forward. Damage below in all it's glory:

[jason1788]

I'm getting it welded up next week. If the welding doesn't work I'll have to take a look at upgrading to separate swirl pot & expansion tank, presumably it must be a step forward. Damage below in all it's glory: