Trouble with the Optimizer 6.5

[littleboy]

I've seen this exact problem with the newer castings. Looks like the rings are not sealing properly and the valves are hitting the pistons which is from the valves not being recessed into the seats properly. Been there seen this exact set of problems before. I'm not impressed with the newer castings. It's all fixable .

 

[uniquediesel]

Good catch on the floating valves. Cylinder #7 shows this.

 

[littleboy]

The valves are not actually floating. It is the intake valve and what happened is that the valve is not recessed into the seat far enough and it is coming open before the piston is leaving tdc. If it was an exhaust valve then it would be a floating or sticking issue. On the newer casting the heads are very inconsistent with valve depth .

 

[jrsavoie]

Thank you! You just made my case! What in the world is wrong with something that lasts for 200k miles.

WOW. Everything is wrong with something that only lasts 200,000 miles. I want at least 500,000 out of an engine. I have 300,000 plus on all of ours now. If I had to replace head gaskets on them every 200,000 I would have unloaded all of them and never had another 6.5 diesel in my life.

 

[bobbiemartin]

I've seen this exact problem with the newer castings. Looks like the rings are not sealing properly and the valves are hitting the pistons which is from the valves not being recessed into the seats properly. Been there seen this exact set of problems before. I'm not impressed with the newer castings. It's all fixable .

Thanks, I'll check this out. The block was rebored +020 and new pistons/rings installed, so I don't know why they wouldn't seat. But you may be onto something about the valves. I'll be out of town this weekend, so maybe next week I can get back into it.

 

[Will L.]

Just for future, that's why you do the wet and dry test.

If the oil in the cylinder raises the pressure back up to where it should be,then you know it is a ring/cylinder wall problem.

If it doesn't, then your dealing with head gasket or valves. To determine that, do cylinder leak down or pull rocker arms and check again. Which have to come off anyways no matter what the problem is the far into an engine.

A lot of people decide to "save time "and just yank the engine out and apart. When you know you're going to be putting in all new parts regardless, then it does save time. When you were salvaging as much as possible, or trying to save money, diagnostic time will replace later guesswork almost every time.

 

[THEFERMANATOR]

I said this back in post #7. Always do a leakdown BEFORE teardown. It elliminates all the guesswork. Then your not looking at it on the stand scratching your head wondering whats wrong.

Just for future, that's why you do the wet and dry test.

If the oil in the cylinder raises the pressure back up to where it should be,then you know it is a ring/cylinder wall problem.

If it doesn't, then your dealing with head gasket or valves. To determine that, do cylinder leak down or pull rocker arms and check again. Which have to come off anyways no matter what the problem is the far into an engine.

A lot of people decide to "save time "and just yank the engine out and apart. When you know you're going to be putting in all new parts regardless, then it does save time. When you were salvaging as much as possible, or trying to save money, diagnostic time will replace later guesswork almost every time.

 

[Will L.]

Yeah you did!!! (where is that emoticon bowing down?)

My only caveat is when a person has already pulled the glow plugs and has a compression tester in hand, a tiny squirt of oil adds only 2 minutes to know the if bottom end is scrappy, then do exactly as you said if wet test shows good bottom end. They have to pull all that stuff off anyways...

 

[uniquediesel]

The valves are not actually floating. It is the intake valve and what happened is that the valve is not recessed into the seat far enough and it is coming open before the piston is leaving tdc. If it was an exhaust valve then it would be a floating or sticking issue. On the newer casting the heads are very inconsistent with valve depth .

You're saying that with the heads you've worked with that the intake valve is opening prematurely and conflicting with the piston during the intake stroke. I see two possible contributors. If cam timing is correct (controlled by the timing chain set) that the minimal recession of the intake valve is causing the interference. Hmm.

I've got a couple new sets of AMG heads here, that we've checked. All in spec and consistent, but minimal recession in the spec.

Something to think about, haven't had problems though.

Out of the defective heads you've seen, what was the recession figure that you found was causing the issue?

John

 

[littleboy]

The ones I saw that were hitting the pistons were only recessed at .30 thousandths if I remember correctly It's been a while since I worked on one the newer heads so I'm not 100 percent sure on the numbers anymore. And yes it was an issue with the intake valve opening prematurely. The worst head was very uneven on the valve recession in the head. They were all over the place. My machinist says he sees a lot of them that have this issue with the newer castings. A simple valve job takes care of the recession issue.

 

[FellowTraveler]

The ones I saw that were hitting the pistons were only recessed at .30 thousandths if I remember correctly It's been a while since I worked on one the newer heads so I'm not 100 percent sure on the numbers anymore. And yes it was an issue with the intake valve opening prematurely. The worst head was very uneven on the valve recession in the head. They were all over the place. My machinist says he sees a lot of them that have this issue with the newer castings. A simple valve job takes care of the recession issue.

Does this issue follow the P400 heads too, or?

 

[littleboy]

I don't think the p400 heads have this issue but I've never had a p400 head to check out.

 

[WarWagon]

FWIW
Keep in mind we have had on here "machining marks" on the pistons and camera effects from the patterns left by the swirl of combustion look like valve contact issues when there were none. I can't wrap my mind around a valve contact issue that was present and lasted for 60,000 miles. Something happened recently to cause this I could understand.

This post shows where the foreign object did cause valve contact and the witness marks are clear. As I recall it bent the valves. Not saying all contact is this clear, but, a visual reference for position. (Something about being useful as a bad example? )
http://www.thetruckstop.us/forum/threads/6-5-carnage.39865/#post-453249

As much as the leakdown test would tell us skipping it means the pistons are coming out for a ring inspection and if nothing is clear I would be X3 and suggest a leakdown is done before the engine gets stuffed back in. Just to make sure the issue was fixed.

 

[300stw]

any updates

 

[bobbiemartin]

any updates

I've been busy with other projects but hope to get back to the Suburban soon. We really have gone back and forth about selling the whole lot or fixing it.

 

[WarWagon]

IMO you don't know what's "broken" on it. This makes repair a harder thing to do and sets you up for heartbreak if the problem isn't fixed before the engine is dropped back in.

Other than the engine how is everything else on it? This may tip the scales one way or another.

I replaced the 1995 of ours with a 2002 5.3L Yukon. AC works better (did require a system rebuild, alternate refrigerant, blend door motors, fan clutch, deslugger, and higher idle engine RPM for this past extreme hot summer) but I don't work on it all the time to the point of ridiculousness like I did the 1995 diesel Suburban. Sure the 1995 had a 1/4 million miles and the Yukon is under 100K, but, still.

We miss the power and Diverter Valve turbo setup, but, I don't miss "the hook" it was getting addicted to.

I'd be first in line to buy stuff if you are parting it out.

 

[bobbiemartin]

OK, it's been decided and the Suburban is officially up for sale!

 

[bobbiemartin]

I'm parting out everything. We bought a new (used) Suburban, a 2003 2500 with an 8.1! Which means, all the 6.5 stuff has to go!

 

[GM Guy]

name some prices! Put a link to the for sale thread.

 

[floyd400]

Nice choice with the 8.1! Definitely a good motor. I hope it works out well for you.