When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I picked up a 54 250 a few weeks ago, it seemed to run decent but I was having near impossible restart issues once it’s hot.
I finally did a compression test and it’s not looking so hot. I only did one bank and I got between 60 and 80 PSI in the cylinders. Then I fired it up and got it hot and tested two cylinders and the compression dropped a few pounds.
I did the test with one plug out at a time and it’s a 6 volt so it won’t crank that fast. The throttle was open. I got about three compressions per cylinder.
It it still runs pretty good when it’s running, is there anything I could be missing?
You must to run a compression test with ALL spark plugs removed and the coil wire removed. Otherwise it isn't telling you anything. Put a squirt of engine oil in each cylinder before you test it.
I agree with Mixer's comment about removing all spark plug before cranking and testing each cylinder. But I would withhold the squirt of oil until you have recorded all readings. If a cylinder appears low, squirt the oil and retest by cranking. If the compression raises, you could have worn piston rings.
I also use a vacuum gauge to do a number of other tests; you could also have bad valves.
I believe the service manual says the 239 should make 125 PSI.
What are are your thoughts on those numbers?
thanks for all of the help.
Chris
I think those numbers are good. And they are all consistent. Last time I did a compression test (dry) on my 54 F100 they were in the 90's.
Look at your battery cables. My 54 starts hard when hot. Last year I took the starter to the auto electric shop to get it checked. It was fine. I knew my cables were good because I had new ones made when I had the truck fixed up and painted...... last week I thought about this again. My truck was fixed up in 1999. So those cables are now almost 20 years old! On Thurs I took the cables to get new 00 gauge cables made. I didn't pick them up yet as I got there after he was closed but on the way out the parking lot he said he cut the old ones open and they were all corroded.
So how old are your cables? And are the 00 gauge? It seems these old engines need max juice when they are warm.
Abe, my cables are not new and they’re probably closer to old. I believe they are 00.
Maybe I will order that set from eBay that we talked about last week in another post. Do you mind giving me your measurements so I can order without having to take my cables off?
Abe, my cables are not new and they’re probably closer to old. I believe they are 00.
Maybe I will order that set from eBay that we talked about last week in another post. Do you mind giving me your measurements so I can order without having to take my cables off?
thanks as always!
Chris
I can do that after I pick them up tomorrow. I'll take some pics too, since you're a a fellow PA guy.
I can do that after I pick them up tomorrow. I'll take some pics too, since you're a a fellow PA guy.
Thanks Abe!
I’ve never been a big believer in additives but this truck might be a good candidate for some mystery oil or Engine Restore for the next few oil changes.
that being said - what oil do you run in your 239’s? I was going to look for a high zinc 10-30. My local auto parts store has high zinc 20-50, that’s a little heavy but I might try it.
I’ve never been a big believer in additives but this truck might be a good candidate for some mystery oil or Engine Restore for the next few oil changes.
that being said - what oil do you run in your 239’s? I was going to look for a high zinc 10-30. My local auto parts store has high zinc 20-50, that’s a little heavy but I might try it.
-Chris
10w30.
I have no experience with the mystery oil. Some guys have used stuff like that. Some swear by SeamFoam.
I’ve never been a big believer in additives but this truck might be a good candidate for some mystery oil or Engine Restore for the next few oil changes.
that being said - what oil do you run in your 239’s? I was going to look for a high zinc 10-30. My local auto parts store has high zinc 20-50, that’s a little heavy but I might try it.
-Chris
I would stick with a good quality 10W30. They all have additive packages in them these days. Make sure that your engine gets exercised while at normal operating temperature at least once a month. You might want to try a good synthetic oil like Castrol. They have less impurities in the oil particularly asphalt-based oils.
The measurements of the cables are this. The one that goes from bat to solenoid is 39", the ground is 12". Here is a picture of them.
As you can see these are not 00 gauge. Here I am one of the guys on FTE saying repeatedly that you need 0 or 00 for 6 volt systems. And he makes me cables with 2 gauge! Last week I told him what I wanted. He said he's got to order the cable as he was out. So today he said his supplier said 6 volt is fine with good quality 2 gauge. And the price of 00 gauge has gone through the roof. Welding cable price has gone up too. But last summer he made me 00 cables for my 55.
I was ticked. I didn't want to blow my top and tick him off as this is the only auto electric shop in the area. I may need him later for generator or starter rebuilds. He promised me these will work fine. I'll put them on and see how they work. They cost $30. If they don't start my truck fast I'll take them back.
He showed me the old cables. They was corrosion throughout. I needed new cables.
