Engine/Transmission (1994 - 1998) Head Cracks

[JoshPeters]

Where do they happen?



I'm now on my 4th Headgasket... . or so I thought. There is only one other thing that can cause the problems I'm having. Cracks. The deck of the head is flat, the block is . 0015 out. This time around I studded the beast. To get away from what I thought was weak Cummins bolts.



Made it just as far as the other times, never going over 25lbs boost... . right around 250miles when I lost heat, and found the overflow bottle overflowing. I am currently trying to find a machine shop that has the equipment to check a head the size of ours.



Any other ideas guys? I'm guessing the crack is in one of the intake runners. None of the pistons are clean, the combustion chambers all look normal. Around the valves looks ok, but I did not remove the valves.



Thanx guys,

Josh

 

[Nick2]

sorry to hear about you bad luck Josh. Have you had the head magnafluxed?... I remember reading a post a while ago about 12v heads cracking when EGT and Mileage go up. I want to say its on the exhaust side (not sure) as that side is a mite warmer. With your luck I'd say any bone yard head would have a better shot at working as long as it's flat. Of course there's always the one in the classifieds for $2000K :-laf .



Nick



PS. I have the 14 15 16 of jan off if you want some help, if that head gives you anymore trouble I could drink a beer at it.



good luck either way



on edit: The exhaust leak theory is supported the lack of clean pistons, as no water would be drawn into the chamber with the exhaust valve open. Also rumor has it you cant easily see cracks in large pieces like this, hence the magnafluxing

 

[Joseph Donnelly]

Cracks usually happen from the valve seat to injector hole, between the valve seats, and elsewhere on the seats. The exhaust seats and valves get pitted pretty badly too. Any decent head shop can magnaflux yours, but I have often seen the cracks without any aid. OTOH, the head porting I did on Sickly resulted in no cracking even at 800 hp. I just got a fresh valve job to go with the new short block before selling "him. "

 

[JoshPeters]

sorry to hear about you bad luck Josh. Have you had the head magnafluxed?

Nick



PS. I have the 14 15 16 of jan off if you want some help, if that head gives you anymore trouble I could drink a beer at it.



good luck either way



on edit: The exhaust leak theory is supported the lack of clean pistons, as no water would be drawn into the chamber with the exhaust valve open. Also rumor has it you cant easily see cracks in large pieces like this, hence the magnafluxing

Thanx Nick, As of right now I'm not sure when I'm gonna pull the head again. I'm out of Cash right now. What will surely be a 5th headgasket, Studs, and one set of cummins bolts have dried me up for a bit.



I agree with your Exhaust theory. I'll do some more looking at it when I pull it down. I'll also be talking to a few machine shops about the Magnafluxing.



Josh

 

[Gary - K7GLD]

Head cracking, at least on some of the older heads, seems pretty common, and sorta makes me wonder about the aluminum head used on the GM stuff, or even the Ford diesel heads - do they suffer more or less cracks than ours - is it a design problem, or does different materials, such as aluminum in the GM stuff greatly affect the tendency to crack... Then, there's our later 4-valve heads - how do they seem to do as far as cracks are concerned?



Some might be inclined to pop in with the opinion that the physically longer inline heads are stressed differently, leading to a higher tendency to crack - but the 18-wheelers are pretty much ALL inline engines (many of THEM are Cummins as well!), and I seriously doubt THEY display the same cracking tendency that seems rather common in our engines...



What gives?

 

[Joseph Donnelly]

The 160, 175, and 180 hp engines don't tend to crack the head. 215 and above do, and bombed engines do a lot. Heat. Those semi engines are inline 6 but they have 3 heads usually.

 

[Bandit1]

at 115k my head just cracked causing me alot of headaches until the crack was finally found, it only leaked when it got hot and was run hard and then it would only seep. a quality machine shop tested the head at 30-40 lbs then at 100lbs and the crack never showed, only after it was reassembled and torqued and then un up to operating temp did the crack show itself. right below the injector hole in the #6 cylinder, **** happens but it is still a good truck and fixing and upgrading are cheaper than buying a new one. keep your head up. if i were you i would save up and look for a used motor and drop it in stock, then when you get more money build your current motor up right instead of patching it. patches never hold, do it right do it once.

 

[Jeff H]

National Bushing up in StCloud can do a submerged pressure check in hot water.

 

[JoshPeters]

Thanks Jeff... I'll have to look into that! That is the first that I have heard of in our area!



Bandit: I have found a new head for a reasonable price..... fully loaded... I will have to see what I find.



Josh

 

[JoshPeters]

Well guys... . I may tear into it tomorrow or this weekend. I'll pop the valves out and see what I can see. Last time I had the head off... I could see no cracks between the valves. I'll keep ya posted.



Josh