Thread: 2.6l 6-pot oil in cylinder #6 - Where is it likely coming from?!?!?!?

Just providing an update on all of those following this thread.

Got the new inlet valves and have installed them in the head. Had my machine shop confirm that the deck of the head was flat and was in spec. Had new valve guides pressed in and was able to get 6 of the guides that have the o-ring recess in the guide itself. As a reminder, the inlet guides in my head had liners pressed into them so no place for o-rings. So the head is back together and ready to be installed.

Cylinder #6 has been honed to remove any glazing although I didn't see any glazing when I used my borescope to inspect. I had a set of rings that Cox & Turner provided that have a better fit not only between the cylinder wall and piston but also a better fit (more snug) in the gap. New piston rings (two new compression rings) have been installed. I was advised by Cox & Turner to use the existing oil scraper rings that I have been using on all the cylinders. As a reminder, the piston rings that I originally installed after the rebuild were allowing lots of oil to pass through the rings gaps and get into the cylinder. Also, the gaps were perfectly aligned when I removed the head and cylinder for further inspection. This is normal for the pistons to move around when the engine is running, but it's not all that common, according to the engine builders I've discussed this with, for all the ring gaps to align and stick there.

Upon further inspecting of the exhaust valves, I found that the #6 exhaust valve was damaged. It was very hard to see, but once I cleaned all the burned on oil and fuel muck off (see pics) I could see, although not visibly obvious, that the #6 exhaust valve was not round. I'm not sure if in the past the valve had come in contact with the piston, or a damaged valve was used as a replacement as a bush fix...not sure, but it was not round. When I shined a light up through the exhaust port I could see light between the valve and the seat. This is probably where most of my issues were coming from. Certainly the compression issues. I'm surprised by this as these were inspected during my disassembly process when I was rebuilding the engine and by my machine shop when I took them the block and engine parts for inspections. Since the engine was completely disassembled, I'm surprised this wasn't found by them. Either way, I'm responsible and I missed it too. This makes sense now and is very consistent with the original leak down test and compression tests results I did when I first got the truck and #6 was by far the lowest.

I am waiting on new exhaust valves and hopefully they will be here prior to Christmas.

In the mean time, I have prepped the engine, removed the radiator, and timing cover and fabricated a tool to extract the exhaust valve rocker shaft in order to get to the #6 valve spring so that I can remove the exhaust valve. It doesn't appear that the #6 valve seat has been damaged as it appears smooth to the touch and all images from my borescope look good.

Shout out to 1950Landy for the drawings of the extractor tool. Made one this afternoon using a piece of 3/8 inch all thread and a #4 Easy Out Stud extractor.

After all of the inspection and testing (compression, smoke and leak down) I feel like I have found all the issues. And it appears, even though the #6 cylinder was firing, the compression was so low that it was not providing much power at all. Can't wait to see how this engine runs with 6 well performing cylinders.

More to come, but have included a few pics of the mucked up #6 valve and the tool for extracting the exhaust valve rocker shaft.
IMG_0018.jpgIMG_0022.jpgIMG_0026.jpgIMG_6307.jpgIMG_6308.jpgIMG_6309.jpg

Originally Posted by matthamilton

Just providing an update on all of those following this thread.

Got the new inlet valves and have installed them in the head. Had my machine shop confirm that the deck of the head was flat and was in spec. Had new valve guides pressed in and was able to get 6 of the guides that have the o-ring recess in the guide itself. As a reminder, the inlet guides in my head had liners pressed into them so no place for o-rings. So the head is back together and ready to be installed.

Cylinder #6 has been honed to remove any glazing although I didn't see any glazing when I used my borescope to inspect. I had a set of rings that Cox & Turner provided that have a better fit not only between the cylinder wall and piston but also a better fit (more snug) in the gap. New piston rings (two new compression rings) have been installed. I was advised by Cox & Turner to use the existing oil scraper rings that I have been using on all the cylinders. As a reminder, the piston rings that I originally installed after the rebuild were allowing lots of oil to pass through the rings gaps and get into the cylinder. Also, the gaps were perfectly aligned when I removed the head and cylinder for further inspection. This is normal for the pistons to move around when the engine is running, but it's not all that common, according to the engine builders I've discussed this with, for all the ring gaps to align and stick there.

Upon further inspecting of the exhaust valves, I found that the #6 exhaust valve was damaged. It was very hard to see, but once I cleaned all the burned on oil and fuel muck off (see pics) I could see, although not visibly obvious, that the #6 exhaust valve was not round. I'm not sure if in the past the valve had come in contact with the piston, or a damaged valve was used as a replacement as a bush fix...not sure, but it was not round. When I shined a light up through the exhaust port I could see light between the valve and the seat. This is probably where most of my issues were coming from. Certainly the compression issues. I'm surprised by this as these were inspected during my disassembly process when I was rebuilding the engine and by my machine shop when I took them the block and engine parts for inspections. Since the engine was completely disassembled, I'm surprised this wasn't found by them. Either way, I'm responsible and I missed it too. This makes sense now and is very consistent with the original leak down test and compression tests results I did when I first got the truck and #6 was by far the lowest.

I am waiting on new exhaust valves and hopefully they will be here prior to Christmas.

In the mean time, I have prepped the engine, removed the radiator, and timing cover and fabricated a tool to extract the exhaust valve rocker shaft in order to get to the #6 valve spring so that I can remove the exhaust valve. It doesn't appear that the #6 valve seat has been damaged as it appears smooth to the touch and all images from my borescope look good.

Shout out to 1950Landy for the drawings of the extractor tool. Made one this afternoon using a piece of 3/8 inch all thread and a #4 Easy Out Stud extractor.

After all of the inspection and testing (compression, smoke and leak down) I feel like I have found all the issues. And it appears, even though the #6 cylinder was firing, the compression was so low that it was not providing much power at all. Can't wait to see how this engine runs with 6 well performing cylinders.

More to come, but have included a few pics of the mucked up #6 valve and the tool for extracting the exhaust valve rocker shaft.
IMG_0018.jpgIMG_0022.jpgIMG_0026.jpgIMG_6307.jpgIMG_6308.jpgIMG_6309.jpg

Thanks Matt, what an interesting topic.


Purely as a matter of interest although it seems your problem may be solved, but for ring rotation on Refrigeration/Air Cond Compressors we used small pins drilled into the piston at a normal Ring Gap & this stopped the rings rotating, so whether this may help you I don't know, but it is certainly positive.

By the by, I read an article some years about a bloke in Papua New Guinea with a Civvy Six who was having problems & I can't recall exactly but I seem to think it was to to do with push rod lengths. He had a hell of a lot of trouble over the years & finished up extending the gap setting more than the factory Spec & I recall him saying that while it was a bit noisy to drive it certainly fixed his ongoing problems.

This may be well known by "Six" owners but it was something I had picked up & figured it may be useful to others.

I "inherited" a used 6 as you do, but didn't want it & could not get any takers except from the scrap dealer after some tea leaf removed all the usable Engine components.

Originally Posted by 4bee

I "inherited" a used 6 as you do, but didn't want it & could not get any takers except from the scrap dealer after some tea leaf removed all the usable Engine components.

I'm slowly becoming a home for orphan 6-cylinder motors, currently 3 spare and one in my FFR.
Seems a few people love the 6-cylinder but most consider them as a boat anchor, mind you you'd need a serious winch to lift that block up from the sea bed !!

Australia probably has more that anywhere else due to the Army using them in all the Series III's, I guess the taxpayer was paying the fuel bills.......

Currently I have one engine that came partly stripped down & I'm considering whether to just save some usable parts like the valves, cylinder head, exhaust manifold, water pump and a few other bits. The alternative is to rebuild but as it came partly stripped I have to first make sure all the parts are present & correct.

My FFR smoked badly when I purchased it but the motor had been 'dusted', new rings & a hone cured that although the bores are at the wear limit. The exhaust note is fantastic and it starts & runs easily without smoking despite being in storage and only taken out now & again.

I keep reading how you need to remove the exhaust manifold to adjust the exhaust valve clearances. I've done it twice now and all I did was remove the dipstick tube and manoeuvre the valve cover out of the way. Time consuming but saves on exhaust manifold gaskets !




Colin

Maneuvering the exhaust valve cover from around the oil dipstick, the exhaust manifold AND the heavy duty oil cooling lines I have installed on this truck makes it a pain in the arse to adjust the exhaust valves. Unfortunately, I do remove the oil filter adapter housing in order to push aside the oil cooling lines, then remove the dip stick and the the exhaust valve cover. Fortunately, since the engine is basically brand new everything comes apart easily.


Most don't find these engines worth the trouble but now that I've seen how they run when rebuilt, I love this old hunk of metal. And the sound is amazing!!!!

Originally Posted by gromit

I'm slowly becoming a home for orphan 6-cylinder motors, currently 3 spare and one in my FFR.
Seems a few people love the 6-cylinder but most consider them as a boat anchor, mind you you'd need a serious winch to lift that block up from the sea bed !!

Australia probably has more that anywhere else due to the Army using them in all the Series III's, I guess the taxpayer was paying the fuel bills.......

Currently I have one engine that came partly stripped down & I'm considering whether to just save some usable parts like the valves, cylinder head, exhaust manifold, water pump and a few other bits. The alternative is to rebuild but as it came partly stripped I have to first make sure all the parts are present & correct.

My FFR smoked badly when I purchased it but the motor had been 'dusted', new rings & a hone cured that although the bores are at the wear limit. The exhaust note is fantastic and it starts & runs easily without smoking despite being in storage and only taken out now & again.

I keep reading how you need to remove the exhaust manifold to adjust the exhaust valve clearances. I've done it twice now and all I did was remove the dipstick tube and manoeuvre the valve cover out of the way. Time consuming but saves on exhaust manifold gaskets !




Colin

Originally Posted by matthamilton

Maneuvering the exhaust valve cover from around the oil dipstick, the exhaust manifold AND the heavy duty oil cooling lines I have installed on this truck makes it a pain in the arse to adjust the exhaust valves. Unfortunately, I do remove the oil filter adapter housing in order to push aside the oil cooling lines, then remove the dip stick and the the exhaust valve cover. Fortunately, since the engine is basically brand new everything comes apart easily.


Most don't find these engines worth the trouble but now that I've seen how they run when rebuilt, I love this old hunk of metal. And the sound is amazing!!!!

I drove a 2A with a 6 fitted, not far, just to move it out of the way & like you I was really impressed even for that short distance. The pull & sound of a well finished 6 was most impressive. I wonder how the Army felt about them after they had tacked on quite a few KM?

"Who is the bastard that signed off on these things #&%$@(%&$?" probably.

I'm sure once they added on all the kit, especially the brush bars mine came with, and tools (the jerry can bases bolted to the back must weigh 40 lbs each) and extra wheels, etc. I bet they were quite sluggish. But stripped of all that and they're not that bad!!!

Thought I would pass along potentially a valuable tidbit regarding the exhaust valve cover seal on a 2.6l petrol engine. Anyone know that the cork gasket/seal is not symmetrical?!?!?!?!?! If you measure from the center of the hole that fits over the studs that secure the exhaust valve cover the distance from center hole to top is not the same as center hole to bottom. From center hole to top is 2 7/16 inches. From center hole to bottom its 2 3/4 inches.

So you know what happens when you put this gasket on the wrong side up??!? The 6-pot pukes oil from the bottom of the exhaust valve cover!!!!!!! Ask me how I know this!!!!!

I couldn't find in any manual I have where it discusses orienting the gasket in any certain fashion. To the naked eye it looks symmetrical, BUT IT'S NOT!!!!!


In case this help one of the few of you out there resorting or maintaining a 6-pot!!!

IMG_6403.jpg

Update on the 6-pot. So, new inlet valves and guides, o-rings and a new #6 cylinder exhaust valve and head gasket (composite type installed dry). Compression on #6 cylinder is now 92%+ when cold!!!! Other than the mishap with the exhaust valve cover gasket I just posted about, the engine is running great with little to no smoke. Compressions look great. Too early to tell about abnormal oil usage and I haven't had a chance to give her a really good break-in run, but soon.

As for now, I do believe, with the help of many on this forum and this thread, I've sorted out the issues of fouled plugs, smoke and missing when under hard load.

I'll keep you all posted on any new events..but hopefully this thread will be closed permanently.

Again, thanks to all who contributed. It really does make a huge difference when troubleshooting an issue. And it is very much appreciated!!!!!!