Welch and Expansion Plugs

[Oakley40]

I picked up my '83 2F from a local engine builder, which went through and completely rebuilt the engine, head and installed all parts except for accessory items. I noticed he replaced the 50mm expansion plugs in the block and the cam plug, which I have to check and make sure it's the right one. But the plugs in the head and the Welch plugs on the front and rear of the block were not replaced.

Is it vital to replace these head and Welch plugs, if they weren't leaking prior to the rebuild?

 

[73FJ40]

IMHO, I would at least replace the plug at the back end of the block, since the only way to get to it later on is to pull the engine.
A number of mudders have noted that these 25 24 mm welch plugs are subject to engine oil pressure in the gallery that runs between them.

I think that the front gallery plug and the head plugs could all be replaced without taking the engine out.

Regarding the cam plug, the OEM has a very shallow cup. When the OEM one is in place, it seemed to me that it almost touched the end of the camshaft. If someone were to hammer in a standard deep cup 50 48 mm plug, I suspect it would have an adverse affect on the camshaft thrust plate.

 

[Oakley40]

Good point on the cam plug. I'm wondering if this was not installed all the way because it was either too deep and couldn't be driven any further (hitting the cam) or if it is the wrong diameter and poor workmanship.

Does the number on the plug look familiar like it is the correct part number, most likely not OEM?

 

[73FJ40]

@Oakley40

I don't remember if there were numbers on the cam plug. I do remember the flange on the OEM one was just flush with the block casting, and not protruding out.

Note that the Toyota one, Cover Camshaft Rear - Toyota (90331-48010), appears to still be available from the dealer, $3.16 list.

 

[Oakley40]

No numbers are on the OEM's. Was hoping it might have been an appropriate aftermarket version. I talked to the shop and they are going to make it right by ordering the OEM plug, check the cam for movement, then install the new plug.

Thanks for the help @73FJ40 !

 

[Bear]

I don't understand why an engine rebuilder wouldn't replace all the plugs--they're not that expensive or hard to do. They may not leak now, but they could be eaten away on the inside or loosened from hot-tanking.

 

[Oakley40]

Was my thought too. While you are in the engine, open everything up so as much as possible so it can be inspected and cleaned. Unfortunately, I have a number of questions regarding the build and this is on the list. Seems to me it's just laziness.

I worry about complaining too much as I don't want the "cook to spit in my food" sort of response. But, I paid too much money to not have it right.

 

[Oakley40]

My engine rebuilder is giving me a bit of a runaround about replacing the cam plug. I don't want him to just replace the plug and not check for damage or clearance issues, but I don't have a good enough knowledge base of what should be done to properly address this.

Based on @FJ40Jim 's thread "How NOT to restore the FJ40", should I be concerned that my thrust plate or anything else may be damaged from them driving in the longer cup plug? How would this be checked and/or what else? The engine has not been started yet.


How NOT to restore the FJ40 post #46
Pulled off the trans, clutch, flywheel, bellhousing. Underneath the BH is found an american standard cup plug in place of the special, very shallow metric cam plug. This plug was beat forward until it was running up inside of the rear cam bearing. Now the plug is occupying space that should be occupied by the camshaft itself.

So if the cam can't fit all the way to the back of the block, what happens?
Well Timmy, if the cam is prevented from going all the way to the back, then when the thrust plate is bolted to the front of the block, instead of the plate pushing the cam to the rear, the cam is going to bow the heck out of the plate and ride forward. Sorry, no pics of that.

So now the cam lobes that normally ride just a little off center of the lifters to encourage lifter rotation are centered under the lifters, allowing the lifters to "stall" i.e. not spin. A stalled lifter tears the surface hardening off the cam lobe in short order, which then begins to destroy the lifter face. And so with only a thousand miles on it, the new cam & lifters and thrust plate are garbage.

But we do get to keep the new all metal timing gear set.

Last edited: Sep 13, 2012
Thanks,
Jim Chenoweth KE8GEF
Underhood Janitor, cleaning up other people's since 1988.
<Useful Desmog Parts FS>
NEW TLC Performance webstore