6.9 IDI valve train questions + head gasket job

Unfortunately my trucks head gasket is leaking coolant front the driver side back corner. I have a 1986 F250 with 150,000 miles on it.

I’m going to pull the engine and stud it. I’m also going to have to take off the front cover of the engine for this job to fix broken water pump weld nuts so it has got me thinking about cams ,lifters and springs.

I will be turbo charging this truck. Would comp 910 springs be a good idea to throw in? I was also considering pulling and inspecting all the lifters. I have heard they have issue’s. I’m also considering a valve job but this truck runs excellent and is relatively low miles so I’d hope it does not need it.

I was planning on using the CDD re-seal kit and head studs. Seems to be the only ones on the market these days. For the head gasket I have always used fell pro but the CDD one seems enticing.

Any thoughts or input would be great!

8769bigred said:

For the head gasket I have always used fell pro but the CDD one seems enticing.

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I think that they are Fel-Pro gaskets. They're just the ones for the Factory Turbo.

8769bigred said:

I was also considering pulling and inspecting all the lifters. I have heard they have issue’s.

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Yes and no. The early ones used bushings for the roller wheel. I might be wrong here, but I thought that they were upgraded to using roller bearings by 1986. You can see the roller bearings when you pull them. As for the inspection, unless you're extremely lucky, I don't think that you can find any issues with a visual inspection.

8769bigred said:

I will be turbo charging this truck. Would comp 910 springs be a good idea to throw in?

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I guess that depends on what you're going to do with it. If you're going to use an aftermarket cam, then it's recommended to use the Comp 910 springs. If you're going to try for big boost numbers, people say that they are goo because a lot of boost can push valves open before their time. Keep in mind that CDD doesn't recommend using them without at least one of those two qualifiers. They say that the stiffer springs will cause premature rocker/push rod wear.

I see ,great info about the springs. I did not consider premature wear due to the extra rigidity. I’m not planning crazy boost numbers. I’m leaning towards a banks turbo kit or a R and D hot side kit. If I could get this truck to 250 HP I would be happy. Having an engine that lasts me a while is important as well. With that in mind I might just toss my springs into the spring tester at work and see how they are. If they are weak I can replace, if not I can re-use.

@IDIBRONCO I have been doing a lot more reading and discovered there are special 7.3 IDIT inconel exhaust valves for turbo applications. Is this a necessary upgrade for the 6.9 when adding a turbo? I have not found much evidence of wide spread exhaust valve failure but if I end up getting my valves done it might not be a bad idea to put the IDIT valves in? Thanks!!

You have to remember that it's the 7.3s that had those issues. Not the 6.9s. It's not the valves that fail, it's the valve guides that wear excessively. I don't know why the iconel valves were used, but I do know that A LOT of people have added a turbo to their N/A engines and have not had accelerated exhaust valve issues. After all of that, I don't believe that iconel valves are required. If you want to use some, that's completely up to you. If you're wanting to go for big numbers, which you're not, then they might be a good idea just for a precaution if nothing else.

@IDIBRONCO ok that makes sense. It seemed to not be a common issue with the 6.9 I just wasn’t sure. I will be taking my valves out to do new stem seals and I will be measuring the guides to see where they. My preference would be that every thing is in spec and I don’t need to go to a machine shop. But projects never go that way do that lol

I made some great progress on this project today. I got the motor out and stripped almost to where I can pull the heads. Crossing my fingers for flat engine block and head surfaces!!

Another upgrade you could consider is using the 1987+ rocker assemblies. They are a better design than the 1986 and down version. They are expensive to buy new though, so a good used set is what I would look for.

@ROCK HARVEY that’s a great idea. I have a 6.9 that I got years ago and I need to dig out the box of parts I think it is a 87 model with the 7.3 arms. I’m hoping I have them. Either way I think I will be doing it even if I have to buy some. Don’t want to have any problems

Heads are off. The gasket looks pretty rough in the back driver corner where it was leaking. Cylinder walls look and there’s no obvious or apparent damage from the years gone by. There is a white substance on some of the valves. Not quite sure what that is. Time to clean

8769bigred said:

There is a white substance on some of the valves. Not quite sure what that is.

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Wes from CDD said what it is one time. I don't remember what he said now. It's not exactly uncommon.

Well good to know it’s nothing crazy!

I might be way off, but I think he said that it's from injectors not firing right. Not having a good spray pattern or something like that.

IDIBRONCO said:

I might be way off, but I think he said that it's from injectors not firing right. Not having a good spray pattern or something like that.

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That’s interesting you say that. The injectors look different than any I have ever seen. They have a star pattern at the bottom and say ‘allied technologies’ maybe aftermarket ? This truck has been in the family since new so I will ask around if any one changed them.

Another odd thing I noticed is I can see the top piston ring. Looks like alot of room between the top of the wall and the piston crown. I do see in the service manual it says to measure the piston below the pin boss so it must have significant taper?