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So there I am, with my new Compression Tester in hand, checking the 235 in my '44 ton-and-a-half firetruck. During the first outing this season, the truck starting stalling out on me, and during pumping, (before the pump broke!) the motor was spitting serious amounts of smoke from the valve cover vents.

I'm thinking the two are not the same problem. Forgetting the (assumed) fuel delivery problem for the moment, my readings on the compression were:

110
90
112
115
75
80

Note: I'm afraid to run the engine enough to warm it up, so this was done cold, AND I did NOT remove the airhorn and prop the throttle open. I DID remove all the spark plugs, well . . . except #2, which was stuck, until I broke the plug and pried it out with a breaker bar . . . I think it was cross-threaded, which could of course affect the compression reading. (and, which may in itself require the head to come off for repair! )

2, 5 & 6 all came up 10 psi after squirting a little Marvel Mystery Oil in the cylinders. I have never had the Valve cover off. Also, I had changed the oil just before the outing, I think modern 10W-30 went in, though I'd have to check.

I'm a rookie at this stuff, mostly, but I would like to rebuild the engine someday, anyway. I just thought I'd solicit advice before I start down that path . . .

Thanks,

-Michael

I think I would look at pulling the head and hope that the head gasket is bad. If not you are probably looking a t a valve job to start. But as always, you clean up the val;ves, then there is more compression and the rings go. So where do you stop? I think at least pulling hte head gasket is a start. Then look at is and he head, see of there is leakage between 4&5, or from the cylender to the outside of the block. There may be carbon buildup, or some damage. Then be sure the head is flat. It is at least worth pulling hte valves and seeing what condition they are in.

Yup, lets be brutally honest: You open up a 50 year old high-mile engine, its likely gonna need a rebuild. Compression goes up after squirting oil in cylinders indicates worn rings. Smoking from the valve cover vent or road draft tube indicates blowby. Serious blowby indicates worn rings, pistons or cylinder walls.

Is this a later full-pressure 235, or the original babbit-beater unit? Unless you need to keep it original, find a later 55-62 235, build it and swap it in. The later 235s are much better, and will look almost identical to stock.

Don't pull the head unless you're ready to decend into rebuildland. Rebuildland is a strange mechanical theme park that has many dark, confusing rides and the admission price is steep.

best of luck

chip

Chip,

It's the earlier, non-pressure lubing 235. I'm partial to keeping it original, so I won't be swapping in a later 235, though I understand why most do. I'm even backwards enough to consider maintaining the Babbit Bearings. And yeah, I'm pretty intimidated by doing a rebuild, but I would really like the engine to be in top-notch shape. AND, among other things, I'm in this hobby to learn. You don't get far in life if you're too scared to step out the door.

So, I'm alright with a rebuild. I've got another firetruck ('51 6400) to play with while this one's down. I WILL probably let a Machine shop do the short block assembly for me. It may be more expensive, but cheaper in the long run versus ruining the engine! Besides, as long as I've got all you stovebolters to constantly pester, what's to worry about?!

I'm open to being educated about the "symptoms" the truck is showing, so I know better next time.

Thanks for the help,

-Michael

How often has this engine been run?

It could possibly be stuck rings,, longshot I know but it will either be stuck rings or just plain worn out.
A rebuild is is due if you want to have a dependable truck,,, OR see what you can do with a cylinder hone, new rings & gaskets and a AAA towing subscription

I'm agreeing with Luke (Mechainiac) on this. Since it is a fire truck, it is probably a low mile engine. I would start by assuming stuck rings. Put the plugs back in. Maybe Luke can tell you an easy fix for the one you pried out. Then warm the engine up and go for a drive on a deserted road. Up and down hard on the throttle several times usually seats the rings. It's the action of the vacuum and the pressure that helps move them. See if that helps the problem, it's a quick and cheap fix if it works. If not, you're in for a rebuild.

If the threads are crossed on the one plug hole, you can use a spark plug thread chaser with a good coating of grease on the end so it holds onto the little chips of carbon & crud and keeps them out of the cylinder.

Never heard of a "Spark-Plug Hole" Chaser - sounds like just the ticket.

I guess puttin' plugs back in and driving it doesn't sound too bad - Heck, I'm assuming REBUILD anyway, so not TOO much to lose . . .

That brings back the fuel delivery issue. After it gets warm, it will usually get to 4th gear before it begins - gradually - losing power, like it's starving, until it dies all together. It will restart after a couple minutes, but the less of a break it has, the sooner it will repeat it's little trick.

Since I put on a rebuilt Carter W-1, I haven't taken it out to test, due to the other issues. HOWEVER, the clear fuel filter I put in just prior to the Carb doesn't EVER seem to FILL with fuel.

My plan was to install a new mechanical fuel pump with glass bowl filter I've wanted to put on anyway.

If that doesn't seem to do the trick, then to heck with it, and I'll get the Gas tank cleaned and sealed and put in new lines WHILE I'm REBUILDING the engine. While I'm at it, maybe I'll just take the cab off the frame, take the tires off the wheels and repain them, have the Fire Pump rebuilt, sandblast the diamond plate, and rewire the whole truck.

Shouldn't take more than a decade . . .

-Michael

I took the head and oilpan off my engine and found a good cleaning, adjusting and some gaskets made for a great running engine. A full valvejob would have given me more trouble as it puts the pressure on the rings etc. I didn't buy an old truck to have a new engine. Just a smooth running and dependable one.

Open it up, clean it up and give it a good tune up. It sounds like it was starving of fuel as well as maybe some stuck rings. give them a good soak when the head is off. Minor cylinder wear will confirm low miles.

One prerequisite to a good compression check is a valve adjustment. If the engine sat for quite a while without being run, sticky vavles are a definite possibility. If you can clean up the damaged spark plug threads without pulling the head, reassemble it, adjust the valves, and make sure it's getting enough gas, then drive it a while. A little crankcase additive like Marvel Mystery oil, or some other lightweight, solvent-type additive will clean up sticky valve guides with a little run time. It's possible the blowby will also diminish as the piston rings get run in to better contact with the cylinders again. If not, a little more run time won't do enough damage to affect the success of a rebuild.
Jerry

Yeah, I can see the wisdom of taking it one step at a time. At the least, I'll pop the Valve cover and see what evidence I find there, and act accordingly. I'll take digital pics along the way, and maybe others can at least benefit from my rookie experience, not to mention stovebolts are better in pictures than in words.

I must admit, though, I'm growing increasingly excited at the prospect of having the engine rebuilt. My goal with this truck is to restore it to it's original, "in service" condition. I've had the original brass hose couplings polished and put on brand new cotten fire hose. A carpenter friend remade the hosebed wood using marine grade varnish - it's beautiful! I've been accumulating the various ladders, lamps, extinguishers, etc. to flush out the truck. So I'm definately gonna want the engine rebuilt sometime, before too long. I love the thought of feeling the way the original firemen felt 60 years ago - with the truck sounding, smelling, looking and performing (almost, anyway) the exact way it did then. Kindof a doorway to the past. A tad bit over-romanticized, perhaps, but that's how I feel.

Did I ever mention I should have been born in the '30s?

-Michael

Mike, a couple of things you may try regarding the engine stalling out because of assumed fuel delivery is to by pass the tank & fuel pump. I've used a graden sprayer connected to the carb. If you have a fuel filter, then you probably have a smaller rubber hose in the line. I take the nozzel off the sprayer and connect the sprayer to the rubber hose. Put gas in the sprayer tank, pump up the sprayer just a few pumps, lock in on, and start the engine. Before you start the engine, remove the fuel line from suction side of your fuel pump. I also put the fuel line which goes from the pump to the carb in a jug, reattach the suction line to the pump to see how the fuel pump is working. The garder sprayer will let you run for a hour to verify your fuel delivery. I'd suspect the line out of the tank is partially plugged. Since you have another truck, swap out the coil, as I have had times when an engine would run OK until the coil got hot and then would just cut out and then won't start until the coil cools down. Hope these suggestions help.

Steve,

Thanks for the suggestion - I had not thought of the coil, and swapping them out is a very practical idea. And bypassing the fuel pump is intriguing as well.

I'll replace the fuel pump first, as I want the more original one on there anyway, then I'll see how it runs, but I think you could be right about the fuel line. If/When I pull the engine, I'm definately pulling the gas tank and replacing the lines as well.

Of course, that will lead to a whole new set of questions . . .

-Michael

My old fuel pump with the glass bowl and strainer leaked bad, and I couldn't find a gasket, so I just bought a new pump on the 10th. It was $25. but it had the glass bowl, so I'm going to trace the new gasket on graph paper and get some cut from a rubber sheet, then I'll install the new pump with its original gasket. I added a strainer under the gas tank where the shutoff valve is, so I've double filtered the fuel.

Auto Zone says they stock the fuel pump, but I bought my from a local auto parts, and I was surprised it had the bowl, it was new, not remanufacuted, and it cost less than Chevy Duty's.

I've been able to find lots of parts at NAPA too.