While thinking about the work ahead of me to repair the cylinder liner seal on my 6v92 that is leaking coolant out of the air box drains (see my other thread), I decided to stick my endoscopic camera through the liner ports and see what could be seen. I was curious to see the condition inside as I was told when I bought the bus that the engine had been rebuilt 25k miles before of which I've added 12k in 3 years.
You'll hear in the video I was thinking that the light from the camera was reflecting off oil and making it look burned and ashy. Now, I'm pretty sure that the pistons and valves look burned. From my research this probably happened when the engine overheated at some point.
I'm now thinking I have an inframe in my future. I'm trying to stay positive as I would have had to remove all this stuff anyways to fix the liner seals.
Can anyone confirm that the pistons are shot? Are the liners or valves gonna need replaced? Is this video too shaky and my breathing too loud to tell what's going on?! :)
https://youtu.be/QHFbpLsYTPE
looks like low compression (to me), need rings.
possibly over fueling..leaky injectors too.
Quote from: eagle19952 on June 24, 2018, 03:42:00 PMlooks like low compression (to me), need rings.
possibly over fueling..leaky injectors too.
Lotta scuffing on those cylinder bores. Definitely will need rings and I wouldn't bet any money that the pistons walls are in good shape, either.
Quote from: Oonrahnjay on June 24, 2018, 05:14:09 PM
Lotta scuffing on those cylinder bores. Definitely will need rings and I wouldn't bet any money that the pistons walls are in good shape, either.
I did not look long enuff to see the thrust sides :)
Quote from: eagle19952 on June 24, 2018, 03:42:00 PM
looks like low compression (to me), need rings.
possibly over fueling..leaky injectors too.
School me on what tells you this. I'm looking to learn how to inspect the pistons and cylinders.
Quote from: Oonrahnjay on June 24, 2018, 05:14:09 PM
wouldn't bet any money that the pistons walls are in good shape, either.
Are you saying the sides of the piston might be damaged or the liner walls? Thx.
Quote from: GnarlyBus on June 24, 2018, 05:52:56 PMAre you saying the sides of the piston might be damaged or the liner walls? Thx.
The scuffing on the cylinder walls means that the lubrication broke down. Probably the rings rubbed dry (or in the presence of overheated, burnt oil) and rubbed grooves in the cylinder walls. I'm going to guess that the scuffing can't be honed or bored out -- or maybe it wouldn't be worth the experiment to try. Once the rings and cylinder walls are damaged, there's a very good chance that the pistons were damaged by rubbing on the rough areas that appear scuffed; this is not a 100%, it may vary on different overheated engines but since it's hard to know exactly how bad it is, it's probably a smart thing to just overhaul that cylinder -- new piston, rings, and liners. If you guess wrong and decide to use damaged parts and they're too damaged to function properly, you've just bought yourself another overhaul either immediately or soon just down the road.
Sorry for bad news, but I'm going to guess that that's the way that it's just going to work for you. If your cylinder walls had been perfect, I'd have said that maybe there's change you got away with it. Your cylinder walls aren't perfect and that's just the way it is; I can't imagine that the pistons got away with no (or minor enough to ignore) damage.
All this is just a WAIG, but it's what I think, based on your video.
Quote from: GnarlyBus on June 24, 2018, 05:51:40 PM
School me on what tells you this. I'm looking to learn how to inspect the pistons and cylinders.
low compression makes an incomplete burn.
the piston tops are flaked//built up with something, (fuel and oil is all it can be)
there should be a visible injector spray pattern on the piston top.
With that much carbon build up on the top of the piston and the valves-either the engine is running too cool, or you're not driving it hard enough, or both. Cylinder walls look good except for three-with that scuff mark on the wall. Doing a ring job, honing the cylinders, cleaning up the carbon deposits and rolling in new bearing shells might be all that's needed. Good Luck, TomC
Not a clean burn at all,that is a lot of carbon for engine with 35,000 miles the spray pattern looks ok, without pulling a head and knowing for sure it looks like some shop screwed the angle grind on the valves and seats ,the glazing between the ports on number 1 is not normal they will glaze the port height .On that one I would be looking at set of pistons and liners and having the heads rebuilt and besides he is only seeing 1/2 the liner
Thanks for the observations everybody. About how much does it cost to have the heads rebuilt?
I have a place in Phoenix I trust to do my work, heads are around $500.00 ea to bring back to DD specs. if not cracked.I wouldn't do liner kits without head work I have done it a few times and they came back to bite me in the @$# every time with a injector tube leaking.It a tough call Jordon but you never know till you open one up I would budget $4000.00 for parts and roll it out and replace the rear main seal too and fix all the oil leaks that is JMO .I tried to post a photo for you of a head from a 8v92 with 365,000 miles it has a no build up
I will be surprised if you don't have a cracked head.
That residue on top of piston looks like ash from oil burning to me. Just tear it down and figure the cost now as Cliff said. You'll regret just a patch job. After repair, verify accurate temp gage readings and especially verify hot light operation and temp setting along with proper operation of overheat shutdown. Consider adding a mister system. Do your first short trips at night in cooler temps and avoid any mountain climbing till you have some easy miles to verify everything is working properly. Radiator and cooling system in good condition.
Quote from: chessie4905 on June 25, 2018, 07:09:48 AM
I will be surprised if you don't have a cracked head.
That residue on top of piston looks like ash from oil burning to me. Just tear it down and figure the cost now as Cliff said. You'll regret just a patch job. After repair, verify accurate temp gage readings and especially verify hot light operation and temp setting along with proper operation of overheat shutdown. Consider adding a mister system. Do your first short trips at night in cooler temps and avoid any mountain climbing till you have some easy miles to verify everything is working properly. Radiator and cooling system in good condition.
I think that is his problem now someone did a patch job in the past
Quote from: GnarlyBus on June 24, 2018, 10:43:32 PM
Thanks for the observations everybody. About how much does it cost to have the heads rebuilt?
The PO of my bus took the patch and go route against the advice of his mechanic. After a number of patch jobs receipts piled up, he finally conceded then installed in a reman motor. Always an expensive and difficult decision but the better path in the long term. Not saying this is for you but something to have on your radar.
Yah, probably best to roll the engine out and do a complete overhaul. It will be much easier to get to everything and do better work.
This has escalated quickly from a coolant leak a week ago. I guess that's how these things go. I'll hope for the best and plan for the worst. We don't really know for sure until we get the engine open, but it helps to be prepared for the possibilities.
We don't have much money into the bus so if it's time to put more in, its definitely worth it to us. It's not ready for mountain cabin status! I'm glad that it has gotten us 3.5 years down the road with only a few small repairs and maintenance.
Quote from: GnarlyBus on June 25, 2018, 11:20:02 AM
Yah, probably best to roll the engine out and do a complete overhaul. It will be much easier to get to everything and do better work.
You could get lucky and find a better running take out...again, do your research :)
Quote from: eagle19952 on June 25, 2018, 11:56:46 AM
You could get lucky and find a better running take out...again, do your research :)
I've seen this said on threads a few times. Help me out, I don't understand the idea of starting all over with another engine unless this one is totally cracked and unusable. Wouldn't a takeout be 2k (for one that needs rebuilt) to 4k (for one that allegedly is in "good" shape)anyways? Wouldn't I have to assume it needs rebuilt anyways so I don't do all the work of replacing it only to find it needs stuff too? Or am I missing something?
Quote from: GnarlyBus on June 25, 2018, 12:22:56 PM
I've seen this said on threads a few times. Help me out, I don't understand the idea of starting all over with another engine unless this one is totally cracked and unusable. Wouldn't a takeout be 2k (for one that needs rebuilt) to 4k (for one that allegedly is in "good" shape)anyways? Wouldn't I have to assume it needs rebuilt anyways so I don't do all the work of replacing it only to find it needs stuff too? Or am I missing something?
let me rephrase.
IF you get extremely lucky. :)
Haha. Ok. :)
Did you ever find out where the coolant was coming from?
If it was getting in the combustion chamber that could account for the ash and the scuffing, although it would be more likely you would have one clean piston if there is a crack. Have the heads very carefully examined for any signs of cracking, also the head gaskets. If the heads are good and you identify the coolant leak as repairable then new pistons, liners and rings are the way to go. Plus a head rebuild of course. The liner kit isn't usually that expensive compared to the overall cost of a rebuild, better to do it right, do it once. You might get by with reusing the parts you have, but the less compression you lose the easier it will start and the more power it will make.
Jim
See my other thread for more info on the leak and a video. It is coming from outside the cylinder so likely a cylinder liner seal.
Right. Well the scuffing in that one cylinder would be the thing that concerns me more than anything else.
Jim
Quote from: GnarlyBus on June 24, 2018, 03:28:39 PM
While thinking about the work ahead of me to repair the cylinder liner seal on my 6v92 that is leaking coolant out of the air box drains (see my other thread), I decided to stick my endoscopic camera through the liner ports and see what could be seen.
https://youtu.be/QHFbpLsYTPE
Your endoscopic camera did a decent job of recording images, is it a more economical camera, or something more pricey? What is the smallest hole it can go into?
If you search Amazon for Depstech endoscopic camera" you'll find some different options from under $20 to $40. They make ones that plug into iphones, androids, laptops, etc. It's pretty cheap if you have something like a smart phone or laptop to plug it into.
The head is 1/3" diameter and the cord is pretty long. They come with attach enemy's like mirror, hook, etc.
Quote from: GnarlyBus on June 26, 2018, 05:21:14 PM
If you search Amazon for Depstech endoscopic camera" you'll find some different options from under $20 to $40. They make ones that plug into iphones, androids, laptops, etc. It's pretty cheap if you have something like a smart phone or laptop to plug it into.
The head is 1/3" diameter and the cord is pretty long. They come with attach enemy's like mirror, hook, etc.
I've got the same setup - works great and definitely worth the money. It's not in the bus along with all the other roadside tools. Lots better than a cell phone on a stick. Mine connects to the smartphone with a direct wifi connection.
I have one similar to yours and hook or tape it to a fish tape to look down drains and pipes etc also. Mine hooks to my laptop or smart phone, etc. i think it was 15.00 on Amazon. don't remember who make it. They do mention to be careful because some of the lens on some units seem to come of.
I have a cheap Harbor Freight inspection camera there is plenty of space in the liner ports for the camera head ,then I have better digital with the FLIR heat imaging feature it is a good camera cost more and I cannot tell the difference on video between the cheap H/F or it,only difference is the H/F gets replaced every 2 years for free lol best 3 bucks I ever spent for a warranty
As long as the crank and cams aren't scored you can do an in-frame no problem. This current case sounds like it was created by overheating 3 years ago and I am sure looking at the video it was using oil. The heads definitely need work, new piston kits, new bearings, and a look of the cam lobs and cam followers. And to do a good job, check the turbo and blower. Rebuilt injectors.
I am just completing my repairs of similar problems on a 6V92 in a 4106. It is laid over 43deg. I had been losing about a gallon every 350mi. Not visible in the oil, but when tested, it had coolant in it. This has been going on for a while (actually since the last rebuild). I took it down at 21K mi since the rebuild. Bearings very worn, but crank OK. Found a bad injector cup (#2). Found leaking at the aftercooler plugs in the air box. The Harbor Freight camera confirmed this by going through the low pistons into the airbox. Found some scuffing on the #6 liner. This is the one right under the leak in the airbox. Found all the o rings deteriorated on the low side (2, 4, 6) liners. Found stuck #1 compression ring on all the low side cylinders. Carboned ring grooves on that ring. Found broken oil control rings on #6. Fixed all this stuff. What has me baffled is why the o ring damage is all on the low side, 2,4,6 where the cylinders are almost level. And why the o rings with damage are the wet side (there are two, one toward the coolant and the other to the airbox for each liner) and all at the bottom. 6 o'clock when looking at the liners installed in the block looking in at the rear of the bus. I used Power Cool since the rebuild. The water jacket is spotless clean. Yes, I have run it hot on occasion, but the leaking was from day one. I have to think the o rings deteriorated gradually. But....
Why does gravity matter? Wouldn't the top side cylinders be more likely to suffer trouble due to hot running?
The o-rings on a liner in a DD last about as long as a snowball in 115 AZ heat if something other than engine oil was used,the after cooler plugs use a aluminum seal on each and are coated Loctite pipe sealant torqued to 270 ft lbs they don't leak if done right and are a bear to remove.If the liners are drove in with a hammer and board then the o-rings were damaged those should go in by pushing with your hand 92 liners need to be fitted just like a 71 series.Usually it is the upper head on a tilt engine that has the problems for lack of water and cooling