Finally tore into the dually

[Dieselcrawler]

well my 85 has been sitting since last August when oil consumption got bad. Comp check netted numbers from 275 to 375. Engine is a 94 7.3T with banks turbo, moose pump and typ4 cam. Last years rally I ran it a little hard and think that's when it got hurt. Well I finally pulled the engine since I sold it. Only pulled the driverside head to see what happened. Well here's the pics.

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[Dieselcrawler]

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[typ4]

When was that cam put in? New springs?

 

[typ4]

What I really want is that cam to check.

 

[Dieselcrawler]

Russ, cam is an older one. Originally sold to goose long ago when he had his promar engine built. I acquired it after the issues he had( which was nothing to do with the cam). No I didn't do springs. Didn't know till after I installed it( about s year ago) that they were recommended. Alex ****** bought the engine off me. I will pass the word on that you want the cam. I got a factory one on the shelf I can give him. @GOOSE should be able to tell you around when he bought the cam

 

[Dieselcrawler]

No new springs, this is actually the first time that I know of that the heads have been off. Engine had 135000 on it when I installed it

 

[GOOSE]

I'm gonna say it was all of seven years ago.

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[typ4]

Well, there were no issues with those. Springs must be weak or something.

 

[icanfixall]

Sure sorry to see damage like this. My thoughts are we "should" replace springs whenever any cam is replaced. Call it insurance or what you will. At the very least check the old springs for open and closed pressure.

 

[Dieselcrawler]

Maybe @tjsea coupd measure them

 

[tjsea]

I think a freind of mine has a valve spring checker. I'll have to have him see what the pressures are on the old springs just for curiosity sake. @typ4 do you believe the weak springs allowed the lifters to pump up and cause this?

 

[icanfixall]

I think a freind of mine has a valve spring checker. I'll have to have him see what the pressures are on the old springs just for curiosity sake. @typ4 do you believe the weak springs allowed the lifters to pump up and cause this?

Exactly my thoughts. When a spring weakens two things happen. They can't pull the valve out of the pistons way so there is contact plus. Adding turbo boost on the underside of the intake valve causes it to blow open easier. Boost pressure is constant anytime you see lbs on the boost gauge. Everything... From the intake bell all the way up to the closed valve has the seen pressure on it. Then the already pumped up lifter opens the valve sooner so contact happens. I can imagine valves with weak springs will close slower causing contact also. Typ4 aka Russ knows his cam and valve stuff very well.

 

[Macrobb]

Can you check the valve recession on the head you pulled off? AKA, put a depth micrometer across the surface of the head and measure how far down(recessed) the bottom of the valve is?

Of course, you'll want to clean all the crud off the bottom of the head first - wire wheel works great for that.

I ran into basically the same problem on my '88 with a /stock cam/. One head had all the marks(and a toasted valve guide on #1), and the other head had /no/ marks(valves did not touch).
Upon measuring, it turns out that the head with no marks was in tolerance per the recession spec, and the other head was like .010 /out/ of spec - the machine shop hadn't ground it deep enough.

 

[Dieselcrawler]

This engine has never been opened up. No machine work done. Head was bolted back on after I took the pics

 

[typ4]

I think a freind of mine has a valve spring checker. I'll have to have him see what the pressures are on the old springs just for curiosity sake. @typ4 do you believe the weak springs allowed the lifters to pump up and cause this?

Very probable, or this is one of those engines that has minimum clearance. I have seen 2 completely stock engines that valves have touched pistons. SO the sheet with the new cam ,If I even do a new cam, will mandate clearance checking. and springs.