cracked block

[amgis_obrut]

anyone had a block crack between the welch plugs before

[stealth]

yes
but was a engine that i machine down for weight and it hydrolic locked at
about 7000rpm cracked the hole exhaust side from 40 to 50 to 40mm plug
it went in bin
why have you got another one?
what happened?
cheers stealth

[amgis_obrut]

kept losing water in the G spec GH and spotted some water marks down near the welch plugs on closer inspection theres a fine crack between all 3 plugs

[stealth]

not good
not good at all looks like your up for a replacement block
could have been weak casting,ive had a few pourus blocks that sweated coolant
at full temp only and one that cracked between cylinders but was bored to 94mm
anyway good luck
cheers stealth

[panda]

I have seen this happen on 4G54 powered Magnas. If you find one of these stuffed motors, grab the head, EFI and manifolds etc.

[cheaterparts]

anyone had a block crack between the welch plugs before

if its any help I have welded 2 different 2.6 blocks both had cracked between the welsh plugs behind the top balance shaft housing

both welded and worked fine -

I removed the welsh plugs - ground out the crack including where it cracked though the
welsh plug holes ( die grinder and small angle grinder )
then heated the side of the block and welded the crack with NiFe cast welding rods
peaning the weld between runs
after welding left the block to cool and die ground the welsh plug holes back to round
fitted some new welsh plugs
I told the owners that it may work - it may not but both cases they were lucky

hope that is some help

[zabatron]

had GE Sigma 2 litre which had a long crack between no 3 and no. 4 welch plugs...one bottle of chemi-weld and it drove fine for 3 years until I sold the car..apparently was a very common problem on early locally built 2 litre astron motors and on early 2.6 litre magnas...I remember my local Mitsubishi dealer had a mountain of cracked Magna blocks out the back in 1986(next to the pile of stuffed magna autos as well).

[Billsy]

the stocker engine in my sig currently has a cracked block, it looks like its been chemiwelded or something as its stopped leaking, it doesnt use a drop of water.

[amgis_obrut]

the stocker engine in my sig currently has a cracked block, it looks like its been chemiwelded or something as its stopped leaking, it doesnt use a drop of water.

is the crack between the welch plugs on the exhaust side of the engine?

[Billsy]

yes, thats where they crack because of the high temp difference with coolant on one side and a red hot exhaust on the other.
if they had a heat shield there i dont think they would crack, or if they had a thicker cast like the later models they are better aswell

[81GL]

yes, thats where they crack because of the high temp difference with coolant on one side and a red hot exhaust on the other.
if they had a heat shield there i dont think they would crack, or if they had a thicker cast like the later models they are better aswell

Hmm... so the shield that is bolted onto the exhaust manifold from factory also aids the problem? helps keep the heat in that area, rather than letting the air easily flow away?

[Billsy]

i dont think so, but a shield underneath aswell to sheild the actual block from direct heat would help.

i am wrapping or hpc coating my manifold when i get to that stage. also for engine bay temps, they go through the roof with all that non shielded turbo gear and no vents