JB weld locations and method 78 SC

[mike sampsel]

I’ve found some things which seem to need JB weld not pictured in Wayne’s book. Thought I’d make sure and ask.

The things in green should get JB weld too?
Same question on the item circled in blue.

And if the blue one gets some, just around the lip? Or some down inside too were the red is?

Trying to minimize the amount of times a future owner can swear at the PO, (me).

[Walt Fricke]

The thing circled in red doesn't look like a plug within a plug, so epoxy would do no good. Wouldn't hurt anything, either, but why?

My experience, such as it is, is that if a plug isn't leaking, why bother to put JB Weld or something similar on it. These plugs are passive - they just close holes, and their grip is plenty strong to prevent their being pushed out by oil pressure, where they are part of that system.

The exception would be the backsides of the chain guide pins on the chain boxes. These pressed in pins are cantilevered and have some force applied to them, and in particular a vibrational force. In the fullness of time oil will find its way out - not much, but an irritant. Porsche put epoxy over them.

Another exception might be plugs you pulled for cleaning or inspection, and then forced a replacement back in. I've never done it this way, so I'd be inclined to add some insurance.

Though when I've pulled plugs, I've just tapped the holes and used a screw plug with pipe thread. Epoxy over that just complicates taking them out in the future. They aren't going to back out on their own. Some are easy to do, and some require great care and fitting if there is an oil passage heading off in another direction right behind the plug. But for an engine which was disassembled just because of high mileage, this kind of passage cleaning (as opposed to brake fluid forced through with air pressure)may be overkill. Can be critical if the engine blew up, since stuff seems to be able to get everywhere.

However, I can't think of any harm you could do by external coatings. Me, I've got enough other things I futz around with so I am disinclined to worry much about unmolested plugs. For instance, soda blasting might clean up a lot of the deposits on the exterior of the case. An aesthetic improvement only, of course, and apt to be a bit short lived as the car gets back on the road.

As you may have noticed, there are various opinions on the best for this or that. I'd never seen the main bearing webs coated with 574 when putting the case halves together. Porsche's procedure shows coating only the periphery of the case. But Wayne's book shows these coated. Recent discussion has had some heavy hitters saying not only is this not useful, but it is positively a potential harm, because it will change the effective main bearing case dimension.

Wayne also shows coating the whole plane of the cam carrier, including the area between the intake and exhaust port sides. Figure 5.9. The rectangle in between these two has no oil holes to seal around, and in fact doesn't even mate flush with the head in between the heads, so why coat that?

These, to be sure, are trivial. Wayne's book is a really great resource. The Porsche manual, for instance, doesn't give a tightening sequence for the head nuts or the cam carrier with all those 13mm nuts (maybe it gives one, but not both). VW manuals always gave a head nut sequence, and Wayne gives us one to follow for the 911s. Very helpful, and helps insure some fastener doesn't get tightened.

Some superfluous epoxy isn't going to make removing plugs harder in the future - you have to drill and tap anyway. And it isn't a sign of temporizing, like lots of excess RTV squeezed out of gasketed surfaces into the interior where it can circulate and may cause problems.

If you want your head to spin with opinions, read the ultimate sealant discussion. Lots of ways to do a functional job.

[mike sampsel]

Originally Posted by Walt Fricke

The thing circled in red doesn't look like a plug within a plug, so epoxy would do no good. Wouldn't hurt anything, either, but why?

My experience, such as it is, is that if a plug isn't leaking, why bother to put JB Weld or something similar on it. These plugs are passive - they just close holes, and their grip is plenty strong to prevent their being pushed out by oil pressure, where they are part of that system.

The exception would be the backsides of the chain guide pins on the chain boxes. These pressed in pins are cantilevered and have some force applied to them, and in particular a vibrational force. In the fullness of time oil will find its way out - not much, but an irritant. Porsche put epoxy over them.

Another exception might be plugs you pulled for cleaning or inspection, and then forced a replacement back in. I've never done it this way, so I'd be inclined to add some insurance.

Though when I've pulled plugs, I've just tapped the holes and used a screw plug with pipe thread. Epoxy over that just complicates taking them out in the future. They aren't going to back out on their own. Some are easy to do, and some require great care and fitting if there is an oil passage heading off in another direction right behind the plug. But for an engine which was disassembled just because of high mileage, this kind of passage cleaning (as opposed to brake fluid forced through with air pressure)may be overkill. Can be critical if the engine blew up, since stuff seems to be able to get everywhere.

However, I can't think of any harm you could do by external coatings. Me, I've got enough other things I futz around with so I am disinclined to worry much about unmolested plugs. For instance, soda blasting might clean up a lot of the deposits on the exterior of the case. An aesthetic improvement only, of course, and apt to be a bit short lived as the car gets back on the road.

As you may have noticed, there are various opinions on the best for this or that. I'd never seen the main bearing webs coated with 574 when putting the case halves together. Porsche's procedure shows coating only the periphery of the case. But Wayne's book shows these coated. Recent discussion has had some heavy hitters saying not only is this not useful, but it is positively a potential harm, because it will change the effective main bearing case dimension.

Wayne also shows coating the whole plane of the cam carrier, including the area between the intake and exhaust port sides. Figure 5.9. The rectangle in between these two has no oil holes to seal around, and in fact doesn't even mate flush with the head in between the heads, so why coat that?

These, to be sure, are trivial. Wayne's book is a really great resource. The Porsche manual, for instance, doesn't give a tightening sequence for the head nuts or the cam carrier with all those 13mm nuts (maybe it gives one, but not both). VW manuals always gave a head nut sequence, and Wayne gives us one to follow for the 911s. Very helpful, and helps insure some fastener doesn't get tightened.

Some superfluous epoxy isn't going to make removing plugs harder in the future - you have to drill and tap anyway. And it isn't a sign of temporizing, like lots of excess RTV squeezed out of gasketed surfaces into the interior where it can circulate and may cause problems.

If you want your head to spin with opinions, read the ultimate sealant discussion. Lots of ways to do a functional job.

Thanks Walt,

I was perusing the ultimate sealant thread about an hour ago. Went from lock tite 574 is the bees knees, to 1211, 1104, (my memory of the numbers is not perfect I’m sure) hike ... and a few other goodies from some heavy duty sealers for sure. It’s certain they have much more sealing experience than this humble poster.

Back to the JB of it: Seems all these plugs were coated with something at the factory. Which is why I’m going to be thorough here.

Thanks for your thoughts always interesting

[Catorce]

I would coat the ones you have circled. It's cheap insurance and there is little reason not to do it.

[Flat6pac]

Just be careful on the one behind the fan, don’t let the weld run down to the fan seat.
Bruce

[Jonny042]

Originally Posted by Walt Fricke

As you may have noticed, there are various opinions on the best for this or that. I'd never seen the main bearing webs coated with 574 when putting the case halves together. Porsche's procedure shows coating only the periphery of the case. But Wayne's book shows these coated. Recent discussion has had some heavy hitters saying not only is this not useful, but it is positively a potential harm, because it will change the effective main bearing case dimension.

If you want your head to spin with opinions, read the ultimate sealant discussion. Lots of ways to do a functional job.

I'm nearing the assembly of my case halves, and have all the sealants. Good God. Been reading all about the various methods and schemes. Seemingly no concensus, even among heavy hitters.

I'd rather read a motor oil thread!

[Jonny042]

Oh and to the OP - my plugs aren't broken, so I'm not going to fix them.

Which is basically what Walt said.

[Walt Fricke]

Orange Loctite (574) is what the factory specifies for the surfaces they say need it. It has worked for me, so I use it. The factory shop manual says that new 574 will dissolve the old, thin, layer, so you don't need to get all the old stuff off. I always knock off extruded hard chunks, but don't clean the rest off, and I've never had a leak. There are others who don't believe what the factory said.

This is the kind of thing where it is your time, not someone else's. Shiny clean surfaces, alcohol wipes, lunar lander clean room, none of that will hurt the result. And there are a number of other sealants which clearly work well and are used by professional engine builders, who as a group aren't inclined just to BS about something - and who suffer financially if their engines leak where they ought not to.

So I suspect this area actually is clearer (as long as you don't make a fetish of "what's the best")than for oils.

[Jonny042]

Originally Posted by Walt Fricke

Orange Loctite (574) is what the factory specifies for the surfaces they say need it. It has worked for me, so I use it. The factory shop manual says that new 574 will dissolve the old, thin, layer, so you don't need to get all the old stuff off. I always knock off extruded hard chunks, but don't clean the rest off, and I've never had a leak. There are others who don't believe what the factory said.

This is the kind of thing where it is your time, not someone else's. Shiny clean surfaces, alcohol wipes, lunar lander clean room, none of that will hurt the result. And there are a number of other sealants which clearly work well and are used by professional engine builders, who as a group aren't inclined just to BS about something - and who suffer financially if their engines leak where they ought not to.

So I suspect this area actually is clearer (as long as you don't make a fetish of "what's the best")than for oils.

Well put, Thanks Walt, for a voice of reason.

Like oil, I suspect there are numerous correct approaches.

[Neil Harvey]

Preparation and attention to detail is what stops leaks, not the sealant you use.