International2cvFriends.com :: View topic - Pushrod tubes (Classic schoolboy error).

Lenny wrote:

So far I've managed to remove two from one of the heads with no great traumas and I've been to B&Q to buy a Rawlbolt to spread the new ones into place. Does anybody have any tips (apart from being a bit more careful in the future)?

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p.s. Are you cutting the damaged tubes flush with the head, then passing the hacksaw blade through the tube to slit it?

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whenever I'm rebuilding an engine, I _always_ fit cylinder heads without the rockers and pushrods fitted.

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A modified rawlbolt works well for expanding the tubes, but take note of the depths at which it should be applied, avoiding those parts of the tube which only have fins surrounding them...

Lenny wrote:

Quote:

p.s. Are you cutting the damaged tubes flush with the head, then passing the hacksaw blade through the tube to slit it?

Yes, that's what I've done so far. Very carefully. Couldn't think of any other way.
I found they just tapped through once I'd made the hacksaw cut.

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whenever I'm rebuilding an engine, I _always_ fit cylinder heads without the rockers and pushrods fitted.

That's what I've always done in the past. This'll teach me a lesson for being too lazy to remove the rockers this time.

Quote:

A modified rawlbolt works well for expanding the tubes, but take note of the depths at which it should be applied, avoiding those parts of the tube which only have fins surrounding them...

Good advice, that. Thanks very much.

Nelsthebass wrote:

Bloody Hell! I must have been dead lucky then in the past as I've never taken any of the precautions above - just whipped the heads off, changed barrels, rings etc., then plugged them back on using my knee to push against the springs resistance and put the head nuts back on...am I naive or what?

2CViking wrote:

No need to remove the valve arms. If piston is TDC (ignition setting) there are no pressure on the push rods.

ken wrote:

Viking,
if an engine's being rebuilt, the rockers will have been removed to lap the valves in, fit new stem seals and so on, so there's really no extra work involved, is there?

Anyway, when refitting a complete head to an engine which is still in the car, there always seems to be some 'juggling around' needed with the pushrods, which is avoided by dropping them in afterwards.

ken

2CViking wrote:

No need to remove the valve arms. If piston is TDC (ignition setting) there are no pressure on the push rods.

Author:	Lenny [ January 27th, 2012, 3:17 pm ]
Post subject:	Pushrod tubes (Classic schoolboy error).
I've had the heads off my engine over the course of the last couple of weeks. I've had the heads off many 2cv engines over the years and never managed to damage the pushrod tubes but this time, for some reason, I've managed to well and trukly knacker three out of the four. I'm a bit embarrased about the whole sorry situation but have now got new tubes on the way and I'm going to replace the battered ones. So far I've managed to remove two from one of the heads with no great traumas and I've been to B&Q to buy a Rawlbolt to spread the new ones into place. Does anybody have any tips (apart from being a bit more careful in the future)?

Author:	2CViking [ January 27th, 2012, 5:32 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
I have 2 tools for the oil return pipes. 1 for original tubes another for reproduction tubes. Reason is that internal diameter is not the same. Remember to smear the tubes with locknut, if not the oil will find its way past. When fitting the heads, undo the valve adjuster bolts to max clearence and set the piston TDC. Smear the push rod seals with grease and gently fit the heads. Tried aluminium welding from a professional welding shop and it worked well, still today. Main issue is to get the distance right from the head flange to the race where the spring washer is seated. Attachment: P7130576.JPG Attachment: P7130577.JPG Attachment: P9150129.JPG

Author:	subarupete [ January 27th, 2012, 5:37 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
very neat tools

Author:	ken [ January 27th, 2012, 6:37 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
Lenny, whenever I'm rebuilding an engine, I _always_ fit cylinder heads without the rockers and pushrods fitted. If you do it the same way, you'll find that it's possible to push the head into place against the light resistance of the pushrod tube seal springs, then spin the lower nut up by hand with minimal chance of knackering the tubes. A modified rawlbolt works well for expanding the tubes, but take note of the depths at which it should be applied, avoiding those parts of the tube which only have fins surrounding them... p.s. Are you cutting the damaged tubes flush with the head, then passing the hacksaw blade through the tube to slit it? ken Lenny wrote: So far I've managed to remove two from one of the heads with no great traumas and I've been to B&Q to buy a Rawlbolt to spread the new ones into place. Does anybody have any tips (apart from being a bit more careful in the future)?

Author:	Lenny [ January 27th, 2012, 6:51 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
Quote: p.s. Are you cutting the damaged tubes flush with the head, then passing the hacksaw blade through the tube to slit it? Yes, that's what I've done so far. Very carefully. Couldn't think of any other way. I found they just tapped through once I'd made the hacksaw cut. Quote: whenever I'm rebuilding an engine, I _always_ fit cylinder heads without the rockers and pushrods fitted. That's what I've always done in the past. This'll teach me a lesson for being too lazy to remove the rockers this time. Quote: A modified rawlbolt works well for expanding the tubes, but take note of the depths at which it should be applied, avoiding those parts of the tube which only have fins surrounding them... Good advice, that. Thanks very much.

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Author:	Nelsthebass [ January 27th, 2012, 7:41 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
Bloody Hell! I must have been dead lucky then in the past as I've never taken any of the precautions above - just whipped the heads off, changed barrels, rings etc., then plugged them back on using my knee to push against the springs resistance and put the head nuts back on...am I naive or what?

Author:	2CViking [ January 27th, 2012, 8:11 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
Lenny wrote: Quote: p.s. Are you cutting the damaged tubes flush with the head, then passing the hacksaw blade through the tube to slit it? Yes, that's what I've done so far. Very carefully. Couldn't think of any other way. I found they just tapped through once I'd made the hacksaw cut. Quote: whenever I'm rebuilding an engine, I _always_ fit cylinder heads without the rockers and pushrods fitted. That's what I've always done in the past. This'll teach me a lesson for being too lazy to remove the rockers this time. Quote: A modified rawlbolt works well for expanding the tubes, but take note of the depths at which it should be applied, avoiding those parts of the tube which only have fins surrounding them... Good advice, that. Thanks very much. I apply a small amount of heat on the head and tap the tubes out with a mandrel. They never bite and slide out easy. No need to remove the valve arms. If piston is TDC (ignition setting) there are no pressure on the push rods.

Author:	ken [ January 27th, 2012, 9:29 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
Nels, I'd say lucky, judging by the number of engines I've found with the ends of the tubes 'clipped' but not leaking all that much. Where someone's really made a dog's dinner of it and completely squashed the tubes, most folk seem to throw them away as they're not geared up for fitting new tubes. ken Nelsthebass wrote: Bloody Hell! I must have been dead lucky then in the past as I've never taken any of the precautions above - just whipped the heads off, changed barrels, rings etc., then plugged them back on using my knee to push against the springs resistance and put the head nuts back on...am I naive or what?

Author:	ken [ January 27th, 2012, 9:35 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
Viking, if an engine's being rebuilt, the rockers will have been removed to lap the valves in, fit new stem seals and so on, so there's really no extra work involved, is there? Anyway, when refitting a complete head to an engine which is still in the car, there always seems to be some 'juggling around' needed with the pushrods, which is avoided by dropping them in afterwards. ken 2CViking wrote: No need to remove the valve arms. If piston is TDC (ignition setting) there are no pressure on the push rods.

Author:	2CViking [ January 27th, 2012, 9:46 pm ]
Post subject:	Re: Pushrod tubes (Classic schoolboy error).
ken wrote: Viking, if an engine's being rebuilt, the rockers will have been removed to lap the valves in, fit new stem seals and so on, so there's really no extra work involved, is there? Anyway, when refitting a complete head to an engine which is still in the car, there always seems to be some 'juggling around' needed with the pushrods, which is avoided by dropping them in afterwards. ken 2CViking wrote: No need to remove the valve arms. If piston is TDC (ignition setting) there are no pressure on the push rods. Agree when overhauling the heads but many DIY folks are fitting new piston and barrel sets without doing the heads. Or many try to replace leaky push rod seals without any work on the heads. By all means if someone can avoid destroying the tubes by taking the valve arms off, go for it.

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