4g54 crack fix

[brendon]

short of replacing the block. my scorpion developed a crack down the thread where the oil pressure switch live.

big switch next to bottom radiator hose (Stock photo from the site, not my car)


thread under the 'b' in the 'alibaba' watermark.

anyways I used devcon and a thread adapter about 2 years ago to repair it, and it has held good until very recently when it began to weep again.

So my plan is to continue to re-devcon the switch/fitting until I can 'reblock' the motor

has anyone got any other thoughts?

[Scorpma82]

a helicoil perhaps....no real permenant fix tho

[brendon]

possibly not sure how it would work I though as that would just replace the thread

the issue isn't the thread itself. there's a small crack down the thread so you can still tighten a fitting (not too tight as the crack widens) to it but the oil travels up around the thread and out the crack.

[Billsy]

you could possibly weld it on the surface, and re-tap the thread.
but the crack will probably re open after not too much time.

[geezer101]

Yep, if you don't want to live with a permanent oil leak it's time for a new block/engine. It might also be a sign of something more sinister going on too...

[Superscan811]

1. Drill a hole in the far end of the crack to stop the crack from growing.
2. Grind a deep V along the length if the crack.
3. Weld up the crack.
4. AS SOON AS YOU FINISH WELDING THE CRACK, PEIN THE WELD. This is VERY important as it will stop the block cracking due to the weld shrinking as it cools.

Steel will just bends when the weld cools but because cast iron doesn't BEND very much, it tends to crack. By peining the weld, it is effectively expanding the metal in the weld. this helps offset the shrinkage during the welding process.

There is another process where you drill, tap, screw in a plug then pein the plug. You do this all along the length of the crack.

OR

grab another block..



Cheers.

[brendon]

Fair enough. Thanks guys I don't think I'm not a competent enough welder to weld cast though.

So I'll hunt for a new block i guess

[Rally_2.6LC]

Hey mate,

Seeing as everyone else has ideas here is my dodgy Rover's fix.

Pull out sender.
Dry out any remaining oil in thread.
Put a little plumbers tape on the sender thread and put it back in.
then surround the thing with "Knead it" wait until fully set and tight before starting...should solve the problem.
Or instead of plumbers tape put the sensor safe gasket stuff around the thread before putting it in.....only problem with that might be not a great earth for the sender.

Or just buy a new block ;)



Cheers
Matt

[SteveG]

Permatex have a green liquid that is a wick type sealant. It can be put on the outside of a nut and "wick" its way down the thread. As long as the crack is free of oil and the oil sender seals all along the bottom of the crack, it may work. Run a bead along the crack and leave over night for it to work down and seal.

I have used it on the join in the cases on my bike and has, so far fingers crossed, lasted 2 years with no signs of leaking.

Part# is 29050 and was fairly hard to get. Had to special order from local parts place.