XM708 engine condition

[JimC2]

Checked the oil level for the first time in about 50 years. Oil was dark, but looked relatively good. No condensation, no crud. Need to blow off the head depressions around the sparkplugs and clean the accumulated crud before pulling the sparkplugs to squirt the cylinders with oil, or maybe Kroil or PB Blaster that I can let sit for a week before attempting to turn the engine over.

 

[NDT]

The oil may look good on the dipstick but it has been my experience on engines that have sat that long, is that there will be about 2” of goo at the bottom of the oil pan. Suggest you drain the oil and stick your pinky finger in the pan to check for this. The goo will block the oil pickup.

 

[G744]

Copy that. Oil's cheap, overhauls aren't.

G744

 

[JimC2]

I agree. That has been my experience as well.

 

[JimC2]

Weather's been too cold to attempt to drain oil and pull pan

 

[ab705]

Do you have a borescope? It would be worth having a look at the cylinder walls to assess the rust (if any) situation before cranking over the engine. If there is a lot of rust, even if you break it loose, it could do some damage when you run the engine: scored cylinder walls, clogged ring grooves, clogged oil control rings, possible damage to ring lands, etc.

I have an old rigid-type borescope that I picked up years ago at a military surplus sale, but I can't always get it into the places that I want to examine.

I recently picked up a flexible borescope attachment from Vevor for my iPhone that produces sharp imagery (1920 x 1440) and allows me to record photos or videos on my iPhone. It has two cameras, one on the end and one on the side of the probe, and variable LED lighting for both cameras. It does an good job for only about 24 bucks, including shipping. And it includes a little hook and a magnet that can be attached to the camera for retrieving objects.



View under the throttle linkage assembly on one of my garden tractors:

 

[JimC2]

I have a borescope that works with my android phone.
I plan to clean the spark plug recesses, pull the plugs, borescope, squirt each hole with Kroil or PB Blaster, let sit a few days, pour in a spoonful of Marvel mystery oil, rotate the engine, and borescope the cylinder walls before cranking it.
If I need to pull the engine, I'll probably do a reversible installation of a Dodge 360 Magnum bored and stroked to 410 c.i. and then overhaul the 230 at my leisure. The 360 installation would be very similar to the 318 installation I put in my 37 before I switched to the big block Chevy.

 

[JimC2]

Didn't get much done today. Reached the truck at 5:30, it's dark at 5:50.
Dropped off some tools and parts, installed the rear lift shackles inside the bumperettes, put a hitchpin in the tailgate linkage, scratched it behind the ear, and left.
Plan to drain the oil tomorrow. Probably drop the oilpan this weekend and work on some damage in the driver's door.

 

[JimC2]

Drained the oil today and pulled the filter.
Oil was dark, but not as dark as I was expecting. No water or condensation. There was about a half inch of sludge in the bottom of the pan, but not consolidated into what I would call goo. Oil filter looked good. I'll pick up a new filter at Memphis Equipment tomorrow and drop the pan Saturday so I can see what I really have going on in the lower engine.

 

[ab705]

scratched it behind the ear, and left.

There was about a half inch of sludge in the bottom of the pan, but not consolidated into what I would call goo.

Speaking of sludge, I'm sure you know that sludge can be a good indicator of several issues, but I thought I'd add a few observations for the benefit of others:

When I pulled the oil pan off the T-245 in my M37, I was happy to find how clean everything was. There was no sludge buildup on the walls of the block itself or anywhere else, which suggests a history of even cooling and an operable thermostat (and possibly a history of detergent oil as well). Running too cold can inhibit evaporation of moisture from the oil and atmosphere inside the block, and can lead to condensation and sludge buildup on any relatively cool surface. Further, an uneven buildup of sludge on different areas of the the inside of the block might suggest uneven water distribution in the cooling system.

Even though things looked good, I still wanted to get a more complete picture of the state of the cooling system, so I pulled off the water pump and extracted the water distribution tube, which I think is a pretty good diagnostic 'tool.' If there is a lot of rust in the system, the slots in a distribution tube are often among the first orifices to be blocked by rust flakes, and the degree of corrosion of the tube itself is a fairly good indicator as to whether the engine had a history of proper anti-freeze with anti-corrosion additives. Mine was pretty clean, without a lot of corrosion, but as long as I had it out, I decided to replace it when I do the planned engine overhaul...probably this coming summer.

New water distribution tubes are available in stainless steel. The old tube can usually be removed with a metal strap with a hook at the end...kind of like a 'slim jim.' If you buy a new distribution tube, it might even come with a removal tool.

A friend with an M37 pulled off his water pump and told me that it didn't have a water distribution tube. I told him to look down the passage with a flashlight, whereupon he saw the remains of the distribution tube; the front of the tube had completely corroded away!

 

[G744]

The water tube is one of the quirky things with the Chrysler flatheads. Another is a tapped & plugged hole over the piston on #6 for making sure where TDC is on #1.

G744

 

[JimC2]

"Another is a tapped & plugged hole over the piston on #6 for making sure where TDC is on #1."

I've been messing with these trucks for 70 years, and I didn't know that.
Thanks.

 

[JimC2]

Changed the oil filter today and worked on the dent in the hood

 

[GopherHill]

Speaking of sludge, I'm sure you know that sludge can be a good indicator of several issues, but I thought I'd add a few observations for the benefit of others:

When I pulled the oil pan off the T-245 in my M37, I was happy to find how clean everything was. There was no sludge buildup on the walls of the block itself or anywhere else, which suggests a history of even cooling and an operable thermostat (and possibly a history of detergent oil as well). Running too cold can inhibit evaporation of moisture from the oil and atmosphere inside the block, and can lead to condensation and sludge buildup on any relatively cool surface. Further, an uneven buildup of sludge on different areas of the the inside of the block might suggest uneven water distribution in the cooling system.

Even though things looked good, I still wanted to get a more complete picture of the state of the cooling system, so I pulled off the water pump and extracted the water distribution tube, which I think is a pretty good diagnostic 'tool.' If there is a lot of rust in the system, the slots in a distribution tube are often among the first orifices to be blocked by rust flakes, and the degree of corrosion of the tube itself is a fairly good indicator as to whether the engine had a history of proper anti-freeze with anti-corrosion additives. Mine was pretty clean, without a lot of corrosion, but as long as I had it out, I decided to replace it when I do the planned engine overhaul...probably this coming summer.

New water distribution tubes are available in stainless steel. The old tube can usually be removed with a metal strap with a hook at the end...kind of like a 'slim jim.' If you buy a new distribution tube, it might even come with a removal tool.

A friend with an M37 pulled off his water pump and told me that it didn't have a water distribution tube. I told him to look down the passage with a flashlight, whereupon he saw the remains of the distribution tube; the front of the tube had completely corroded away!

The water distribution tube is very important on these engines. Make sure yours is in good condition.

 

[G744]

I've seen replacement tubes in brass, I wonder if they last longer?

G744

 

[ab705]

I've seen replacement tubes in brass, I wonder if they last longer?

Pardon the long-winded response or topic 'drift."

I'm not a metallurgist, but I think brass in contact with a cast-iron engine block would represent a greater difference in the galvanic series than stainless steel against a cast-iron block. Brass and stainless steel are both more 'noble' than cast iron, and in both cases, the iron block would act as a sacrificial anode and corrode to protect the brass or stainless tube, although any sacrificial corrosion of the cast iron should be slower with a stainless tube than with a brass tube.

I'm not sure what kind of steel the original distribution tube in my M37 was made of, but IF the tube was made of, let's say, mild steel, which is quite close to cast iron in the galvanic series, that should reduce (but not entirely stop) dissimilar-metal corrosion. However, the anode-cathode relationship would be reversed, since cast iron is slightly more 'noble' than mild steel, so a mild steel distribution tube would act as the sacrificial anode to protect the cast iron. That said, any dissimilar-metal corrosion between mild steel and cast iron should be very slow, and even slower if you always kept your antifreeze (with corrosion inhibitors) up to date, which of course would help reduce corrosion with any of the above combinations of metals.

The original steel water distribution tube in my '54 M37 was still in reasonably good shape...a little rusty, but not too bad. The tube in my friend's M37 had corroded away, probably from a long history of expired or inadequate antifreeze and corrosion inhibitors.

On a related note, when installing a brass thermostat in a cast-iron head or block, I think it's a good idea to use a non-conductive gasket that will prevent direct metal-to-metal contact between the brass thermostat and the cast iron.

 

[JimC2]

"The water distribution tube is very important on these engines. Make sure yours is in good condition".

Yeah, I figured that out somewhere around 1962 when I first had a problem with it.

Worked on dent removal in the hood and driver's door today. Made headway, but still a long way to go. Supposed to be warm Wednesday so I may let dropping the pan slide till then.