Knock Knock

[Diamondwhips]

So I have been a member here for about a year getting lots of great info. I have come to a problem that I can't pin down and would like some advice. So here's the deal I bought my truck in February and have had starting problems from the get go. First problem was air getting into the fuel system and bad glow plugs. Once I fixed those and about 3 months after I got in the truck one morning and got a series of knocks that went away. Nothing for a week or so then it's knocking again on a cold start but clears up.
So I'm thinking either bad injectors or bad injector pump or both. I get a hold of Mel and get a new pump, injectors and return line kit so all should be good. Next morning 2 knocks and the truck is running rough for a few seconds than its fine. I'm thinking *** and call Mel to see if he has any insight as to whats going on and he thinks it could be a bad valve guide. The reason he thinks this is because you can hear a huffing sound through the intake when the starter is turning the engine over.

So here's my questions, does anyone have a good way of testing to see what guide or guides are bad without pulling the heads?
Is there any other things I should be looking at to determine what might be wrong?
At this point I'm about to part this thing out but want to make sure.

The truck in question is a 1992 Ford F250 NA bone stock with the exception of a larger exhaust and a new transmission

 

[Can30Diesel]

I believe Riotwarrior has some experience with a failed valve guide.

I believe from his pictures, pulling the valve covers will let you know which one is going. Look for the dirtiest place.

I'll let others chime in.

 

[Diamondwhips]

I believe Riotwarrior has some experience with a failed valve guide.

I believe from his pictures, pulling the valve covers will let you know which one is going. Look for the dirtiest place.

I'll let others chime in.

Yea I saw his post about valve guides and it was helpful. I did pull my valve covers and everything looks fine. When the valve covers were off I tried to give each valve a good shake to see if I could feel play. I did find one but I think it might be more likely that the rocker wasn't putting much if any pressure on the valve.

 

[79jasper]

Injectors are real close to the intake, may be why you can hear it there.
(Of course unless you took your truck to Mel in person, then go by what he said)

You can loosen one injector line at a time to see if it goes away.

Sent from my USCC-C6721 using Tapatalk

 

[Wellused]

When I had a 6.5td break a valvespring,I had the upper intake off(air cleaner for us) you could see the offending cyl puffing right up #3 intake runner in the intake while running.Maybe you could try it.I dont know what holds the screen over the intake opening as I have not had to ever remove mine

 

[Wellused]

Being new to the 7.3idi world..I just pulled up a youtube video of the valvetrain.Bolt in non adj fulcrums just like Oldsmobile(I have spent enough to get kids thru college getting around oldsmobile non adj rockers)I will guarentee some of the shot guide threads and broken valve threads are directly related to worn fulcrums.As the wear(fulcrums) it changes the contact patch on the bottom of the rocker which adds side loads to the valve stem.There i9s absolutely no way to adjust/compensate for wear,decking block,valve jobs and head shaves with this setup without milling valve stem length above locks or custom pushrods to put the rocker in correct arc/travel.

 

[Diamondwhips]

I'm going to try a test to see if I can isolate the problem. But I still have a questions I can't seem to figure out.

What causes the Knock sound if the noise is coming from the valve train? I thought knocking was either pre-detonation or a piston knock.

Why is the knock only every once and a while (like weeks apart) shouldn't a mechanical problem be consistent issue?

 

[marvgarr]

It could be lifter drain back when cold and started for the first time in the morning it will have a slight knocking sound if it is only one. You said you pulled the valve covers off was it dirty inside sludged up? If it is a lifter you have to replace it nothing will fix it I have had this problem on a lot of vehicles one of them sounded like the rod was going to come through the block. Once it warmed up it wouldn't do it again and only would do it if it sat for more then a day you could drive it everyday and it would never do it let it sit for a couple and knock knock. What oil do you use? How many miles?

 

[Diamondwhips]

It could be lifter drain back when cold and started for the first time in the morning it will have a slight knocking sound if it is only one. You said you pulled the valve covers off was it dirty inside sludged up? If it is a lifter you have to replace it nothing will fix it I have had this problem on a lot of vehicles one of them sounded like the rod was going to come through the block. Once it warmed up it wouldn't do it again and only would do it if it sat for more then a day you could drive it everyday and it would never do it let it sit for a couple and knock knock. What oil do you use? How many miles?

I was kinda leaning towards a lifter as well. So I was going to try to use the starter (with the injector pump shut off solenoid disconnected) to build oil pressure then try and start it. I figure that would isolate a lifter problem.

When I had the valve covers off they were a little more gummy then what I'm used to seeing (first time with a diesel) but nothing like the pictures I've seen when there's a bad valve guide.

I use 15-40w non-synthetic 175,000 miles

 

[marvgarr]

How long have you had the truck? What brand of oil if it is delo/delvac/rotella/motorcraft it has high detergent and if the po had ran crappy oil and never changed it the new oil will start loosening up the sludge and get stuck in lifters and oil passages. I like to run rotella it has higher detergent then delvac delo also is higher keeps sludge at bay my .02.

 

[Diamondwhips]

So I thought I would post a picture of the rocker arms and such just to give everyone a look at build up.

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[marvgarr]

So I thought I would post a picture of the rocker arms and such just to give everyone a look at build up.

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That is sludged up looks like the 6.5 I tore apart for rebuild. Try running a cleaner in the oil maybe it will remove some of it.

 

[Diamondwhips]

I'm starting to think the PO didn't change the oil much. After your last post I was leaning towards running some cleaner through it but I thought the pictures can't hurt. I'll run it with a cleaner until the next oil change (about a 1000 miles) and pull the covers and see if there's an improvement

 

[Zaggnutt]

Thanks for the clear pics... You've just convinced me that I have a shot valve cover gasket....

Would running ATF in the fuel filter/let it sit/run it like hell the next day loosen that up? Several guys here suggest it for loosening gunk.

If it was my engine and my problem, my concern would be putting a new gasket on, putting cover back on, reassembling everything, running a cleaner for a while.... just to have the problem still be there. I would want to check all the mechanicals while I had everything apart so I wouldn't have to do it twice.... I'm a beginner compared to most of the contributors to this forum, but I HATE doing the work twice especially because I was to lazy or timid to be thorough the first time. (I am not assuming you are either - strictly my perspective)

 

[icanfixall]

I feel thats not lots of sludge build up at all. I would run some Auto RX thru it. then feel thats all it needs as far as cleaning goes. As for the atf in the fuel filter. Thats for cleaning out the possible gummed up injection pump or injecters. You fill the filter with atf. Run the engine til you hear a distinct sound change and shut it down. Let is sit over nite. then you the hell out of it the next day. That usually flushes out the possible gummed up injection system..