Dove Tunnel Wedge casting porosity issues & solutions.

[undy]

As discussed in earlier posts my Tunnel Wedge on my KC 482 has coolant porosity issues. A weld/machining repair was conducted and there was/is still minor coolant leakage into the oil, although now in small amounts. A block sealant was added and it's seemed to stop 95% of the seeping. I finally got somewhat fed up and called Dove myself this AM. They introduced me to a patented process called "IMPREX". In layman's terms it's "Vacuum Casting Impregnation". The company that owns the process is called Godfrey & Wing Co., out of Ohio. I called them and talked to technical. They were very knowledgeable and helpful too. This is a standard process for aluminum castings. Their tech mentioned that they just received 4,000 aluminum engine blocks from GM for the process application. They have standing contracts with most of the major automotive MFRs. Rather than go into a bunch of technical verbiage I figured I'd just post their web site. Thoughts, points and counter-points would be greatly appreciated. Let me know what you think...

http://www.godfreywing.com/vacuum-casting-impregnation/

[ERA Chas]

Dave,
Did they quote a price to treat your TW?

[cobrarkc]

Do you know if you can machine the piece after it has been treated? Like say you want to port match.

[undy]

Originally Posted by ERA Chas

Dave,
Did they quote a price to treat your TW?

They said the minimum charge is $150 and that the manifold can easily be done within that amount.

Originally Posted by cobrarkc

Do you know if you can machine the piece after it has been treated? Like say you want to port match.

You can machine afterwards, understanding that the area machined will not have the coating. I would heartily recommend machining THEN treatment though.

[xlr8or]

How about Dove paying for it?? They made the faulty part.

[undy]

Originally Posted by xlr8or

How about Dove paying for it?? They made the faulty part.

I didn't buy it directly from them and it's been over a year anyway. The vendor I bought it from valiantly tried to repair it. Too much water's gone under the bridge to try to recoup $$ at this point. I really don't care about the money. I'm just wore out dealing with it. Dove's customer service really isn't stellar in the regard.

[Grubby]

I use to be a Manufacturing Engineer with Navistar (supplier of the Powerstroke to Ford), and that repair method was used from time to time for salvage of preproduction engine blocks and intake manifolds. It was not considered acceptable for production engines going to customers. There were concerns with long term sealing.

Good luck.

John

[undy]

Originally Posted by Grubby

I use to be a Manufacturing Engineer with Navistar (supplier of the Powerstroke to Ford), and that repair method was used from time to time for salvage of preproduction engine blocks and intake manifolds. It was not considered acceptable for production engines going to customers. There were concerns with long term sealing.

Good luck.

John

The guy I talked with at Godfrey & Wing seemed pretty sharp. He said that they would do 2 consecutive treatments. Evidently the process will accept some layer building. I'm going to attempt to limp through the summer and plan on doing the tear-down this winter. If things get worse I'll be forced into acting sooner. If the plan prevails then I'll have more time to research the process further. I'll look into the possibility of longevity issues also.

[ERA Chas]

Originally Posted by Grubby

It was not considered acceptable for production engines going to customers. There were concerns with long term sealing.

Too bad GM didn't know this before they sent over 4000 blocks for treatment...

[joyridin']

Originally Posted by ERA Chas

Too bad GM didn't know this before they sent over 4000 blocks for treatment...

Wanna bet they knew? LOL

[Sizzler]

Do you have to account for the coating when machining for tight tolerances? Or does it all get "absorbed" into the metal?

I'm thinking the press fit holes. Like when you get things chromed and they have to mask off those areas.

[Grubby]

I was a GM manufacturing engineer for 15 years before Navistar. You can bet they know the risks.

Many times there is a balance between delivering something or delivering a good product.

In my opinion, Navistar made the right call. We only fixed pre-production type engines. They were run in test mules or on dynos and then scrapped. If there was a sealing failure, it did not hurt their reputation.

John

[undy]

It sure looks like Chrysler and GM have some long term faith in it if they're using it in their production engines. Their site hosts a video of the Chrysler V6 aluminum blocks getting impregnated. Maybe the process has been improved?