I've watched this fellow on occasion. Just thought this could help others using this engine.
OOPS! Nice catch. Perhaps it would be good to subscribe to the guy that saved his arse?
Also the sign of a "rush" mechanic, an eye needs to be looking for that sort of stuff. Yes he is a fairly sharp fellow, thought I have seen him do some things I would not. Also note one of the commenters in this video mentioned this. "Take a look at SIS document M0064312, I think that's the information you're looking for." Can anyone here post what that says? I would not want to be running as much as they did with the bridges on the retainers like that. Back in the day I remember those dowels getting oil under them and bending push rods, etc etc.
I don't think he's a rush mechanic but I'm not there so who knows? 50k engine, nice
I saw it too. Honest of him to post it up like that. I would guess that Cat did not do a good a good job disseminating that info if neither he nor anybody at his shop knew about it. You can tell he does read his manuals but something that important should have a bulletin with a yellow and black border and exclamation points all over it.
Actually-That's Cats fault. Because there are two styles of crossheads, the replacement cylinder head should automatically come with correct crossheads to avoid a catastrophic failure. Especially if that cylinder head has a upgraded design. What the hell, Cat would charge for them anyway, built into price of cylinder head. Most all gasket sets for automotive engines come with replacement head bolts.
It is a Service Magazine announcing the introduction of floating valve bridges to replace the former bridges that were supported on a dowel. Interestingly it ONLY refers to engine models in the 3400-series powered by natural gas , so I wonder *** it has to do with this engine.? Wondering out loud without watching the video I wonder if they used a mixture of parts from a diesel engine valve train valve train arrangement and a natural gas one to rebuild the engine.? The 3406 engine arrangement for the D8N ONLY lists non-floating (dowelled) valve bridges, so somehow that engine got either the wrong cylinder head on it, or wrong valve train parts. I would've thought whether new or Reman a head would come with the dowels already installed. I didn't think I can recall ever seeing an engine in an 8N with floating bridges. 3500 bridges were a totally different animal. They were originally dowelled then went to 100% floating. Even older engines were all retrofitted when they were overhauled. I found his comment about never having to adjust bridges when checking valve lash interesting. They must be totally different to a 3500 because at the time for setting bridges/valves on an old version of that engine the bridges were always out by a hair and you'd have to reset them before setting valve lash.
Obviously no one stuck their tongue out and made sure of the serial Number. That being the case.
Looking at the other videos of him working on this engine the valve bridge setup was wrong for the tractor when he pulled it apart. The valve covers have "Cat Reman" on them, so either Cat Reman in Corinth MS built it wrong in the first place or it was the wrong Arrangement for a D8N. Then when he got the replacement head it had the dowels in it to suit the correct valve bridges for the D8N installation. So instead of asking "why the difference?" he went ahead and pulled them out. If he'd stopped and looked at SIS at that point he'd have realized that the originally-installed floating bridges were wrong and the new head required the "right" ones with the adjusting screw. The solution was not pull out the dowels so as to be able to fit the existing bridges.. He works for a Cat dealer and has "full fat" dealer access to SIS. IMHO he should have been looking at all of this when he pulled the engine apart, especially as he is a self-professed on-highway engine guy rather than an earthmoving equipment specialist. Doubly so seeing as he says he investigated "all service documentation" regarding cylinder head/valve gear, etc, etc. EDIT: It's all a bit disappointing TBH because I like the guy and follow his channel from time to time. After this experience maybe he should stick to on-highway engines.
There is a little info missing. This is a reman engine under warranty for high oil consumption. He's not actually being a tech on this one he's just turning wrenches. He did not decide, irc, to pull the dowels. The engine was running for 10 hours a someone at cat called the dozer back to change the valve bridges.
The video in the OP is just the final video of a series of 3. I watched the first two, and on the basis of them is where my comments in the post directly above yours were made. Without watching those two videos there is no context.
This is how I have to edit my posts since there is no edit button days later. Also what does that SIS document say?
Nige posted it above. "It is a Service Magazine announcing the introduction of floating valve bridges to replace the former bridges that were supported on a dowel. Interestingly it ONLY refers to engine models in the 3400-series powered by natural gas , so I wonder *** it has to do with this engine.?"
It's always been the case that you only have 5 minutes from first posting in which to edit a post. After that the text is locked to everyone apart from the moderators.
Is that all it says?
My text above is a precis of what it says, and it is applicable only to certain specific natural gas powered variants of the 3406 engine, not the whole 3406 product line. The point being that it is NOT relevant to the engine in question because, unless I've missed something over the years, the 3406 in a D8N runs on diesel not natural gas. I don't know how much clearer I can express it.
So then the original head had the gas engine valves in it? Since they were tall enough to keep the bridges off the retainers. Do they just add some sort of insert in the injector hole for the spark plug?
No idea. I've never seen one. I would imagine the natural gas variants are probably used in genset applications mostly in the oil & gas industry, and that is an area in which I've never been involved. The point i was trying to make was that the Service Magazine mentioned in the YouTube comment did not apply to this D8N engine so that whole avenue of thought was a total red herring. To get to the crux of the matter would need the engine Serial Number or Arrangement Number (or both) of the Reman engine. If the Arrangement Number on the plate was identical to that of the original engine in that tractor for D8N application then IMHO the finger should be pointed at Cat Reman who built the top end of the engine to the wrong spec, mixing parts from diesel and natural gas variants.
cat does provide the crossheads with a reman head
Although the service mag only references gas engines, the floating bridge is an update across a large range of the 3400 family and the fact that they were installed in the reman engine is legitimate. Although, granted, it hasn't been particularly well documented in SIS, to start pulling the dowels out of the new head without digging to see what's going on is fairly unforgivable IMO.
Standard modern engineering, with a cross section like that I would expect that happening. Especially with a casting.
Another thing that makes me hope i dont have to go back to mechanic work. Its one thing if you just work on cats but if you work on all brands its that much worse. I wonder if this has happen before . I watch this guy some i may go back and watch it agin.