The incredible shrinking manifold

[Jack fr MO]

Have I missed an article or what on this problem, "the incredible shrinking manifold"? At what mileage are they breaking on the 12 valve engines? My truck is a 98 12 valve and I began receiving the the TDR magazine with issue "22", but don't remember anything about this problem until this article in issue "37". Is there any more wisdom on the subject out there that can be shared?

 

[illflem]

My feeling is some vendors are just trying to scare us into buying their manifolds. I'll fix mine if it breaks, nothing sooner.

 

[Joseph Donnelly]

I'm not trying to scare you about your 12 valve exhaust manifold. Look at the upper #1 bolt holding the manifold to the head. Look from the trough not the bolt head side. you will see that the manifold shrinks until the bolt is at the edge of the hole in the manifold. Later you will see the bolt is bent, because the manifold has shrunk more and the hole in it no longer lines up with the hole in the head. Eventually the bolt will break or the ear will break off the head from the strain.



On the 24 valve, the manifold just cracks. I can show you one cracked almost into two pieces.

 

[Pit Bull]

Joe what causes some to crack and others not to crack? Do they all crack eventually? I checked mine and it looks good from the top. Got under the truck with a flash light and could not see a crack from the bottom, but it is hard to get a good line of sight. Will I see a crack in the top or only the bottom? If it is only seen fromt he bottom, when it cracks is it easy to see? I read the article but it did not explain I you easily detect the crack. Sorry for all the questions

 

[Motorhead]

Cracked 12 EX manafolds

At the UPS center where I work, We have about 15- 12v powered Ford chassis, A UPS package car is probably one of the hardest driven vehicles on the road. I haven't seen any of them crack an exaust manafold yet. They are '95's & 96's. Several have well over 150,000mi. There are only two positions on the throttle of a UPS truck... Idle and wide open on the governor:--) Chris

 

[Joseph Donnelly]

It is very rare for a 12V manifold to crack. It just shrinks lengthwise. You change it mostly to protect the head, secondarily for quality, airflow, and failure-free driving. The more heat, the more shrinkage. Thus, high hp and high mileage Rams and Rams used for heavy towing have more trouble.



It is pretty common for the 24V to crack, either on top or bottom, usually near the center. Again, more heat seems to aggravate the problem, but luck of the draw seems to be part of the equation. The worst one I have seen was a stock ETH used for heavy towing. The whole top of the engine was a soot ball from leakage.

 

[Pit Bull]

As long as it is covered by the 100K warranty, I'd want mine to crack at around 90K

 

[KWentling]

I read this topic this morning before servicing the truck. Getting ready to haul hay. I looked at my manifold and you can see the shrinkage has the front bolt pulled in at least 1/8" I can see no cracks either in the manifold or the head. 64,000 miles on the truck. Makes me wonder if it would be smart to go with the AST manifold now rather than letting the 100,000 mile warranty cover it should it fail within that time frame. I'd hate to have a cracked head even if it were covered. Wonder if they would deny coverage because of the TST plate?

 

[Jack fr MO]

Thanks everyone for the input

I'm thinking the same thing as KWentling maybe I should replace before I get out on the road in "who knows where" and I have a problem that may not be easily repaired. Wondering if there will be any specials at the Hall of Gotta Havits in Columbus IN at the TDR Natl. Rally. Would be nice if they knocked a $100 off or so. LOL Thanks again.

 

[David Oxland]

I've seen several broken exhaust manifolds on other engines due to shrinkage and bolts being loaded up to the point where the manifold cracks.

I've often wondered if a person were to elongate the bolt holes in the manifold slightly he might delay or even avoid the situation it's likely the end ones.



A metallurgist might be able to explain what's happening to the cast. I've wondered about carbon or some other element depleting with the heat.

 

[Joseph Donnelly]

Slotting the holes would delay the inevitable. Changing the mfd is enough hassle, and you have to buy all the gaskets. I'd rather do it right, once.



The cast iron has silicon in it.

 

[fj40charles]

Any realationship to manifolds cracking and not allowing your engine to cool before shutdown? I figured it would not be good to quickly heat or cool down the manifold. Has anyone gone many miles without cracking their manifold? It seems like this is a design flaw if it is happening so frequently.



Charles

 

[illflem]

Jack, apparently the ATS is on sale somewhere in the tdr mag, I can't verify as I haven't received mine yet. One person has contacted me by phone and another by email wondering about the "coincidence" that the manifold write up and sale come at the same time.

My feeling after working on tons of 12 valve CTDs and seeing only a few cracked or broken manifolds is that my modification priorities lie elsewhere. Can't speak for 24 valves. Of the cracked manifolds I have seen the owners have related to me that they ran at very high egts more than they should have or ran modified without gauges. I highly doubt that a stock engine or one whose owner keeps his egts down will ever run into a problem. Do keep an eye on your manifold but it's your buck if you chose to go the prevention route.

 

[R.E. Miller]

Just an idea here, look at how the big boys come from the factory. Like the N-14 has a three piece, and others like the m-11 too... I think. Of course the N-14 has three heads, so that only makes sense

Just a thought,

Russell

 

[Joseph Donnelly]

In TDR #37, there is a picture of the 12 valve exhaust manifold and the ATS replacement on p. 29 (note the caption vs. photo is incorrect becasue the ATS is under the stocker; similarly, the stock vs. ported 12 valve head captions are reversed. (My article)



A cracked 24 valve exhaust manifold is shown on p. 56. (Bill Swails' article).



The only advertisement that I found mentioning the ATS manifold was Mr. Bob's on p. 135. The ad didn't mention price or a sale on it.



I bought and installed an ATS manifold on my Ram over 2 years ago.

 

[David Oxland]

This problem is not peculiar to this engine. I've seen it regularly on constant running engines such as generators. Constant temps not running excessive temps: 700-800F continous. But that was after 20,000 hours. One solution is expansion pieces or slides.

 

[JTMcCracken]

It happened to my old 1990 W-350, it shrunk enough to break the top, front bolt. I had no luck getting the broken end of the bolt out with ez outs and ended up drilling it out completely and putting in a longer bolt with a nut on it. JTMcC.

 

[hammersley]

Joe -

My TDR mad is at home - wanted to check with the add ---



The only advertisement that I found mentioning the ATS manifold was Mr. Bob's on p. 135.



Can anybody give me the phone number for Mr. Bob's????

 

[Ram4Sam]

Right here.......

http://www.mrbobsdistributing.com/contact.ivnu



or better yet...



http://pub44.ezboard.com/fwwcd2grouppurchasesfrm3.showMessage?topicID=195.topic



Sam