M1151A1 HMMWV plenum crossover removal

[rcamacho]

I’m following TM sequence to service LH valve cover gasket. Plenum crossover and LH manifold must come off in sequence so as to not bend injection lines.

TM 9-2320-387-24-2
Sections
15-20
15-16
16-4
15-11

The problem is there is not enough clearance to remove crossover from turbo outlet. A pillar close out panel and dog house retainer have been removed per TM. Need 1” more clearance. Note crossover is not the cut and welded version.

looks like I have to lift the whole body or pull the turbo off.

 

[HoveringHMMWV]

Hmmm? I decided to try and remove my crossover without following the steps in the TM for the A-pillar close out and doghouse retainer. I had a couple inches of clearance and it looked doable. I was able to successfully remove my crossover with those in place, so not sure what’s going on. If I remember correctly, I had to lift vertically and rotate the crossover forward (clearing the turbo output) to gain the clearance (with heater duct/hose removed).

 

[rcamacho]

I’ll try again a few more times. Perhaps the body mounts are compressed but they look ok.
Almost have the turbo out anyhow.

 

[Mogman]

IIRC the original GM cross over has a higher profile than the GEP cross over.

 

[Retiredwarhorses]

You’re body mounts have sagged over time, you will need to remove the 2 fronts, Jack up the body with 2 floor jacks about a 1/4-1/2in to gain the clearance, when you put it back, you might want to add an additional spacer to keep the clearance for later on….or just replace the mounts altogether.
also…the valve covers do not use a gasket per sey, they use sealant only, make sure to use a new valve cover.

 

[rcamacho]

Yeah planning to use RTV black ultra, no gasket

 

[Retiredwarhorses]

Yeah planning to use RTV black ultra, no gasket

i would use and I use “grey” high temp..

 

[rcamacho]

i would use and I use “grey” high temp..

Which mfg/type of grey?
Presume high temp rigid….

 

[rcamacho]

 

[rcamacho]

Body mounts are definitely compressed. Followed advice and raised the body a tad. This plenum is definitely taller as well

 

[TOBASH]

There are two crossover sizes, as per Mogman’s prior post. The GEP is smaller. Tight on my ECV, but not problematic. Not sure if they are interchangeable BUT if they are you could consider swapping.

Best,

T

 

[rcamacho]

Ordering replacement body mounts now.
Per TM 9-2320-387-24P-C05
My 1151A1 is sub 3K serial number however it looks like the mounts can be updated to the new style.
Ordering a few 5340-01-568-4874

"AMG STARTED USING A NEWER VERSION OF THE MATERIAL IN 2019 TO RESOLVE THE ISSUE WITH THE CRACKING THAT WAS BEING EXPERIENCED IN PRIOR VERSIONS" -HPG

 

[Retiredwarhorses]

There are two crossover sizes, as per Mogman’s prior post. The GEP is smaller. Tight on my ECV, but not problematic. Not sure if they are interchangeable BUT if they are you could consider swapping.

Best,

T

for all intents, there isn’t ’..…having had both units, the modifed crossover was used on early m1113 when AMG was still using up all of GM’s left overs, you will find civilian Turbo intake manifolds on many rebuilt GEP engines, the civilian manifolds are different as they have the provision cast into them for boost sensor and other emmisions related components.
With proper body mounts and spacers, in the OP’s example…his body mounts are worn and compressed over time, there is no need for a modified crossover. The difference in being able to get the crossover off and not getting off is literally a 1/4in.

 

[TOBASH]

having had both units, the modifed crossover was used on early m1113 when AMG was still using up all of GM’s left overs, you will find civilian Turbo intake manifolds on many rebuilt GEP engines, the civilian manifolds are different as they have the provision cast into them for boost sensor and other emmisions related components.

So in other words there are two different castings.

I bought my truck from you… the body lift was and is perfect.

 

[Retiredwarhorses]

So in other words there are two different castings.

I bought my truck from you… the body lift was and is perfect.

right, but saying to go order the old isn’t a thing…ordering a new one will net you current production Part.
The OP’s truck is an Armament carrier, thus is had MCTAGS mounted on top…much heavier than what was on your 1st generation M1165

 

[Retiredwarhorses]

Here is the old version part no.RCSK17829

M998 HMMWV INLET MANIFOLD 6.5 TURBO | eBay

ONE EACH NEW 2815-01-439-8163 RSCK 17829.

www.ebay.com

In the Govt parts world, the NSN does not change, the part number changes, so I searched the NSN on eBay…thus it produces both types, when you search the old part number on distributor web sites, you get the current GEP mfg’d part, RCSK17829 is a Mfg discontinued part.

 

[rcamacho]

I’m looking forward to seeing the old upper mounts out for inspection. From what I can tell they are all significantly compressed

 

[rcamacho]

I have the LT plenum and #1,3,5 injector lines off. Stuck on #7 as I can’t seem to get the crowfoot & wrench on from a LT attack position. Really would like to avoid having to remove the RT plenum and even numbered lines just to get #7 off.

 

[Retiredwarhorses]

I have the LT plenum and #1,3,5 injector lines off. Stuck on #7 as I can’t seem to get the crowfoot & wrench on from a LT attack position. Really would like to avoid having to remove the RT plenum and even numbered lines just to get #7 off.

You don’t need to remove them all, just bend the injection lines up out of the way carefully…No, the lined are not lined as some people like to say.

 

[rcamacho]

valve cover off now. Typical gasket over tightened and warped cover