Dirt Daily The Flatfender gets a Compression Test 

Run it a little bit and see if the compression comes up. Very little time and effort invested to find out if it really is toast. Those are very tough engines. Love the flatfender series.

So there are a few issues with your methods. First, don't put plugs back in the cylinder you just tested. Makes the starter work harder against compression and also means the engine is turning at a slower RPM each time you do this. By the time you reached #4 your battery was weak and the starter was fighting the compression of 3 cylinders. Notice that the manual states the PSI at a given RPM. It's a certainty that your test on #4 was not at the same RPM as #1. Second, open the throttle plate and prop it open with a screw driver. Or better yet, remove the carb altogether since you're probably going to have to rebuild it anyway. You want maximum incoming airflow into the engine for a compression test. With the PSI you have on the first 3 cylinders this engine will certainly run right now. Fire it up, get some heat cycles into it, and test it again and I'm sure #4 will improve. Don't spend anymore money on it until you hear it run because there's also a possibility of a spun bearing and rod knock on the bottom end.

try dumping some marvel mystery oil in the #4 hole and see if it frees up the rings.

Sticky rings maybe, I would pick up some Yamaha Ring Free and try that. A leak down test would verify if it’s rings or possibly burnt valves.

"It's it a waste of time? Yeah. But is it fun? Definitely!" Best quote ever!!

Run it ...get it Hot...a few times..then See... Pluss your battery was getting weaker..you can hear it...pluss I would leave All the plugs out...for the whole test.. Your the Jeep Dude...Run..It!!!!

Get it running and see if that cylinder maybe loosens up whatever is clogging the rings

A bleed down test will let you know where the compression is escaping to. Or carefully use compressed air in number 4 cylinder and listen for air escaping past the valves or into the engine case on the power stroke. For the 4th graders, remember the crank can move once you start to compress any cylinder so keep fingers etc clear if you don’t have the piston at the bottom of the stroke. But like everyone said, if it needs a freshen up anyway no harm trying to get it to fire?

I’m thinking you get it running and those rings on number four are going to free up Love the Flat Fender

Bet it'll run fine once you get some heat into it. Hopefully just a stuck ring.

Woo! More Flat Fender!!!

My experience tells me to pull the valve cover and pull the head. When I started working on my 45 MB it started, ran, and bang. A piece of piston broke off and that piece did not compress and smashed into the head and broke my original to the engine Head. I wound up going thru 2 heads until I got one that would work. Pull the Head to inspect. It will make good RU-vid content.

These videos are perfect timing, as I'm working on my 48. I hope you replace the rings so I can see how you get the head off!

Best robot dance ever!! Totally enjoying this Flat Fender series.

Great video topic and great comments in the comment section. Keep up the videos 👏

Really enjoy the slow speed you are teaching us, explaining the thought process in a laid back way is very encouraging. Thank you for these troubleshooting skills you are projecting with our part time hobby!

Great basic info Fred and very clearly explained.

Sometimes if the engine has been sitting or has been stuck the rings get stuck and can't expand to seal off the cylinder. If you run it a bit and burn out some of the carbon buildup it may loosen the rings and allow them to seal again. You probably already know all this anyway but I thought id share in case you didn't. Something else to try is substitute a quart of ATF type F with your engine oil and run it for a few hundred miles and change it. Ive had that trick work a few times on motors with low compression.

Great video, like others said, put a little Marvel down that hole. I marvel at the mysteries that stuff solves. Love this series, good job. 😂

Perfect for pulling it, dingle ball hone, valve lap and running....

That’s my upcoming weekend right there!!!! Excellent!!

This video reminded me about the time I got a flat tire on my 73 Country Squire station wagon while off roading in DFW at 360 and Old Man Ed answered my CB call for help with his 42 Ford GPW and aired my tire with a Spark Plug Tire Inflator from his Jeep. He said it was a military issued tool. How a Spark Plug Tire Inflator works ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-jTTVVmV_--s.htmlsi=bzNI8Qgfy5ULwZKm

I have 2 observations that may be helpful. 1.The engine rotation speed seemed slower as you went along . 2. At 16:44. That far right valve looked like it was closing really slowly. Perhaps a bit of penetrating oil in the #4 intake tract cound free the valve up in the guide.

You are excellent @ explaining what you are doing to all! The compression over-all a little underwhelming, no?

I might've missed it but when testing make sure the throttle is held wide open and the exhaust pipe is not plugged.

Spay a little mystery oil in each cylinder crank it over then let it sit a day or so. Could be sticky valves or piston rings

I’ve been watching for awhile on this particular project. Being that it had been stuck/seized. #4 was most likely the stuck cylinder this could account for the lower compression in that cylinder. Also like others have said. Your test is not entirely accurate. I do agree with getting it running and see if #4 comes back around. The rings may be a little sticky in the piston and a couple heat cycles might loosen them up. I definitely can’t wait to see the next video on this.

I would fire it up. You might have bore taper and a ring is stuck in the piston groove. If you give it an Italian tune up it might come around.

Fred, I'm with you on trying to get this one to run. Fuel and spark and see how it runs. Before pulling the engine, I think I would pull just the head and see what the #4 cylinder looks like as well as looking to see how the valves are seating. That will give you a better idea of how much of a rebuild you are in for before you pull the engine. Maybe it's just new rings and a dingle ball hone but if you see scoring in the cylinder walls, you know it's going to need more than a hone and some oversized pistons.

My favorite engine swap I've seen is a Mazda rotary in a flattie

The little engine that couldn't. But have fun.

Get it hot and make it work. The compression will come back they always do!

Like others said: penetrating oil, get it running, and drive around a bit.

Great content! Are you interested in sponsorship on vehicle lighting stuff?

ive never see a CJ2 or 3 with a Jeep 2.5 with efi thats a combo id try just to keep it all jeep

Razzel, Dazzel, Brazzell from OHI. Has anyone put a Pontiac Iron Duke four-cylinder engine in one?? I enjoy your show.

Run it the rings may come around after a heat cycle or two. They are tuff.

Suck..Squeeze...Bang...Blow.... gotta have all those things for the engine to make itself useful.

I’ve done the rice or water down the carb to break up build up on the valves as the engine was running and have also just poured gas and oil mix in the cylinder and set it on fire and let heat up things. I’ve either had good result or no results. These were all old engines that have sat forever and and were believed to be no good anyway. All old timer tricks on engines that were old as dirt.

Could be a stuck ring. Maybe it will break loose. Fingers crossed!

My gut says WD/ATF/MMO the piston daily while putting the ignition and fuel systems together. Fire it up and get it warm a few times. The compression ring is siezed and needs a few shocks to loosen it up. 70 percent of factory isn't all that bad; it's not like it's a high performance engine in any case. If it's only 40hp max? That means it's still got 37 of them left!!

Hey Fred when are you and dirt head Dave gonna get together again for cheap truck challenge or a trail ride?

You're really milking this one!! Video # 1,209,000 haha love the show brotha!!

I heard to open throttle wide open when checking compression.

Nailed it

Maybe running it will knock those rings loose?

I would try to start the engine Fred, warm it up if possible, and then recheck the compression

Get it running on 3, and let it warm up. Could just be a stuck piston ring is all, and some time and heat will fix it.

Time for a ford v8 flatfender!

Either way you gotta pull the head to see what’s up. Just run it. If it sounds like hell after 20 seconds, shut it off and get ready to start tearing it down. If it starts running decent, 🙌🍺

Are you blind or just play a blind guy on you tube?

Fred you need an M151A1 MUTT

If the engine is original, rebuild it. If not, Take the Best Body, frame, the New Engine/Trans/Transfer Case and make one Awesome Flat Fender from all your parts !

Dude!!! Stuck ring? Get running, puts some heat in her!!! Then a hemi swap!!! Lol!!!✌️

that is not a waste of time, you have to try to get it to run even if you already plan to swap it out

Get the engine running and run a Berryman Products 2611 Intake Valve and Combustion Chamber Cleaner and see what happens.

LS time ! 😃

How far has Fred gone down to.

With 25 psi it can never be a "stuck" valve not closing. That would always be 0 psi.

Probably should adjust the valves.

Do a cylinder leak down test... see if air is coming out the crank case, (rings) or the intake/carburetor (intake valve ) Or the tail pipe ( exhaust valve )

Seafoam my friend

Throttle should be held open full while cranking.

Keep plugging away at it

Vakve springs are upside down

Jimmy Nylond may have the answer!

There's a whoooole lotta experts down here in the comments

It would be blasphemy but a mercedes om616 or an om617 would be cool

Why did you put the #1 plug in.

Some of your vavle springs are upside-down.

75% good or 3 quarters. That's a pass.

head gasket maybe

Was this video made for 4th graders? “This is an engine, it’s made of metal..” 😆

leak it down fred you're better that that

Just rebuild it

no bueno!

Rather than fix the problem, you want to keep fooling around with a broken engine....

Yeah, a Japanese motor would be inappropriate, to say the least....