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Keep blowing gasket between EGR cooler and exhaust manifold

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I purchased a new 2008 GMC T7500 in 2010. It has the 6H series 260 hp Isuzu engine. We are full time RV'rs so I had it custom made to tow our 5th wheel and carry our 2 ATV's and 12' aluminum boat. In 2014, 11 months before my extended warranty expired in 2015 it started squealing and eventually blowing the EGR cooler to exhaust manifold gasket when the exhaust brake engages. This gasket was replaced several times then eventually the EGR cooler too. They also discovered moisture from a coolant leak internally, something I complained about for almost 2 years. They eventually replaced the EGR cooler 2 more times as well as the exhaust manifold because the gasket kept blowing, all to no avail. Then they tried a new exhaust brake and that made no difference so put my old one back in. Isuzu engineering suggested custom cutting a copper gasket and some sort of special mounting bolts like they use in racing cars. These also failed recently. They think the bolts are stretching from overheating as they always seem to loosen, but they don't know why.

If It was always the same dealer I would say they don't know what their doing, however, I've dealt with 3 different Isuzu dealers in Canada and the US and none of them can resolve this issue. Isuzu can't figure this out and don't want to play anymore so it looks like I may have to take them to court. Apparently I'm the only one on the planet with this issue! Does anyone have any ideas?

Thanks

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Delete it, imo getting rid of all that EPA junk is way better for the motor and your wallet if your out of warranty. I'm assuming it has a durmax though

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It may eventually come to that if Isuzu won't fix it under my now expired extended warranty. Thanks for your input!

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Dang I think I'd like to see pictures of the truck. I bet its cool.

Anyway stretch in studs is very common. Especially if its been overheated a couple of times. I'd see if ARP makes a set of studs for this.

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Thanks for your suggestion! They did try a set of special bolts and they loosened as well. Here's a couple of pics for ya.

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Nice rig. Thanks for showing it.

So are the bolts loose causing the gasket to go? Or gasket blowing then bolts loosening?

I would chase the threads to make sure they are OK and getting the proper torque new bolts/studs and use copper spray on the gasket.

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They think heat is stretching the bolts then blowing the gasket. Also happened with a new EGR cooler and exhaust manifold installed.

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Also how small is the EGR cooler? Could it have warped from the heat? Maybe worth having a machine shop look at it to make sure its truly flat.

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Thanks for your questions. It's the factory EGR cooler and I've had 3 replaced as well as the exhaust manifold.

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So I'm not familiar with this exact engine. Are the housings all replaced? This would give you 2 new, flat mating surfaces. Should do this at the same time. Also the new studs and gasket with copper spray. Thats what I would do.

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As stated in my original post, the EGR cooler as well as the exhaust manifold that it bolts onto was all replaced at the same time previously, and included all hardware.

Further to all this, last month on our way back to Canada we had the gasket again replaced at Rush Truck Center in Fontana, CA. The squeal returned within 192 miles. Once back in Vancouver, BC I took the truck into my dealer and they discovered the rear mounting bolts for the EGR cooler were missing and there was now a crack in the EGR cooler above where it mounts to the exhaust manifold. I phoned Rush truck explaining what my dealer found and sent photos that were sent to me. My dealer also spoke to Rush Truck and sent additional photos. I emailed Rush Truck a copy of my $1427.00 bill for reimbursement and heard nothing from them. I later phoned and left a message and again heard nothing. I finally reached them this morning and they claim that they mounted and torqued the bolts properly and have no explanation as to how they could fall out. So with their analogy that would be like taking your vehicle in for new tires, however one of your wheels fell off after the install. Can't explain how that's possible as we torqued all the lug nuts. 

So be aware of Rush Truck Center in Fontana, CA as they do not stand behind their work!!

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Some GM vehicles had trouble with the header to exhaust flange doing this. Their solution was spring loaded bolts. I wonder if this might work? I've cut copper gaskets myself and switched to the spring type with more or less OK results.

Here's an example: Exhaust springs.

Oh, way cool rig. :thumbsup: 

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Thanks for your suggestion. I'll check with my dealer. The thing is, in the world of Isuzu, I'm the only one on the planet with this issue. The new EGR cooler with a new gasket just installed is again squealing!???????

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Looking at your pictures it appears theres a boss at the side of the block to hold one end and the other bolts to the exhaust manifold. If yours truly is the sole unit doing this then I would suspect the dimensions between the mounting points are off.

This is further affirmed by the crack I see in one of the pictures. I'm betting the mechanics are not noticing the unit binding as the bolts are being tightened. I see absolutely no other possibility from the pictures you've posted.

Honestly I don't care for the design. As the exhaust manifold heats and cools it's going to slightly change the relationship of the front to rear mount, not really ideal. It would almost seem leaving the front mount bolt off and rebracing the unit in a different manner might prevent cracking. 

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My dealer says the crack developed because Rush Truck Center forgot to install the rear mounting bolts which they deny. The three previous EGR coolers never had a crack. The first one had a coolant leak that took them 29 months to figure out as I was always having to add coolant, and the other two were desperate measures to try and fix the squealing gasket. Thanks for your input!

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You would think that in this day and age we would have absolutely bulletproof diesel motors......why not perfect it and than improve slightly as needed.....

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1 minute ago, rmxtgh said:

You would think that in this day and age we would have absolutely bulletproof diesel motors......why not perfect it and than improve slightly as needed.....

We had bulletproof motors but emissions regulations keep getting more stringent.

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We had bulletproof motors but emissions regulations keep getting more stringent.


Yep now all kinds of crap hanging off them, electronics etc. Has reduced reliability.

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