Looking for opinions - compression low on 2 & 3

[HDowse]

KGBnut, your HF leak tester sounds like a good idea. Could you list the parts you purchased and any assembly details? I’d like to try it on my A.

[KGBnut]

I followed this video.

https://www.youtube.com/watch?v=JWmefGONh_g

Ignore all his part numbers, they are out of date, but I used them to make a shopping list. You can likely get better quality parts at your local hardware store, but I made mine with mostly Harbor Freight Parts. I think I bought one pneumatic parts assortment that contained most of needed parts.

He talks about filling a fitting with epoxy and drilling a hole. The perfect hole is apparently 1mm by 6.7mm (6.7mm being the depth of your epoxy plug). If it is not exact, the tester will still work, but the "percentage of leakage" reading will be off. I just tried to get it as close as I could with the tools at hand. Mine reads almost exactly the same as my buddy's high-dollar kit. Close enough for me!

The hose I stole from my compression tester. Just make sure keep track of the Schrader valve... in for compression tester - out for leak-down. Or, you can buy the hose separately on Amazon if you don't have one.

https://www.amazon.com/Powerbuilt-64...3920724&sr=8-3

I mostly use this tool on my motorcycles. You need an adapter to fit the larger spark plug threads on a Model A. All the major suppliers have them for use with compression testers.

https://www.snydersantiqueauto.com/P...earchByKeyword

Here is a pretty good video of how it is used on a motorcycle. I couldn't find a video of it being used on a vintage automobile, but the procedure is really the same. Maybe I should make one...

https://www.youtube.com/watch?v=CC1EZCxDnLc

Spend some time and do some research. You can buy some complete kits pretty inexpensively. I just like to make things and find I understand tools better when I make them myself.

I hope this is helpful.

Ken

[Patrick L.]

For an automotive type leak tester I just use a spark plug base with an air fitting welded in. An air line connects to it with a shut off valve to control the air to the cylinder. Not much air pressure is needed to find the leak.

[HDowse]

Thanks, Ken, for all the information and video links. I have a number of those fittings and HF is fairly close by for the rest so I'll put one together next week.

[nkaminar]

Depending on the size of the leak between cylinders, you may be able to hear the leak by taking out the adjacent plug.

[alexiskai]

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Originally Posted by KGBnut

I built my own leak-down test kit with parts from Harbor Freight for about $25.

For those without the inclination or ability to DIY it, you can buy gently used kits on eBay for a decent amount. I spent $55 to get an OTC 5609 kit. You can run these kits at 90 psi.

[shew01]

I found this for $36 on Amazon.

Cylinder Leak Down Tester,Compression Test kit - Engine Cylinder Dual Gauge Leakdown Tester kit Diagnostics Tool. https://smile.amazon.com/dp/B07W9FXK...62MQ450B580CK8


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[old31]

For $36 delivered, why take the time to build your own. That's a no brainer for me.

But wait. Look at this. $26.00. Now this is a no brainer.

https://www.amazon.com/ABN-Cylinder-...motive&sr=1-11

[alexiskai]

I opted for the OTC kit because these generic ultra-cheap kits just look sketchy. Poor reviews, a lot of DOA units, and it appears that they operate at very low pressures.

[Jack Shaft]

Wet/dry compression testing tells the story..an engine wears evenly,if,for instance doing a leak down pinpoints #3 exhaust valve..okay,do you just do #3? Or does the engine get a complete valve job? If the other valves than 3E still seal,they are surely worn as much as 3E,they just haven't burned yet.The same with piston /cylinder issues..do one? Or do them all? An engine performs best maintained consistently,with all cylinders in equal condition.

[JayJay]

Originally Posted by alexiskai

For those without the inclination or ability to DIY it, you can buy gently used kits on eBay for a decent amount. I spent $55 to get an OTC 5609 kit. You can run these kits at 90 psi.

I use the OTC 5609 kit as well, same reason - name brand inspires a bit of confidence in me that it will work well. Yes, you can easily assemble your own, but I have better uses of my time.

I did find that using this kit at close to 100 psi on the Model A is enough to push the piston down, so be sure to put it in gear before your test.

You can also do the leakdown test with piston down to see if you can hear bubbling in the radiator that might indicate a cylinder wall crack.

JayJay

[alexiskai]

Originally Posted by Jack Shaft

Wet/dry compression testing tells the story..an engine wears evenly,if,for instance doing a leak down pinpoints #3 exhaust valve..okay,do you just do #3? Or does the engine get a complete valve job? If the other valves than 3E still seal,they are surely worn as much as 3E,they just haven't burned yet.The same with piston /cylinder issues..do one? Or do them all? An engine performs best maintained consistently,with all cylinders in equal condition.

In my case, a leakdown test pinpointed #2 exhaust. I pulled the head and found that someone had put an undersized valve seat insert on it, which had come loose. Engines wear evenly, but humans make mistakes unevenly. Sometimes you're just correcting a mistake.

[Jack Shaft]

Originally Posted by alexiskai

In my case, a leakdown test pinpointed #2 exhaust. I pulled the head and found that someone had put an undersized valve seat insert on it, which had come loose. Engines wear evenly, but humans make mistakes unevenly. Sometimes you're just correcting a mistake.

Rare...but you still had to get into it

[old31]

Originally Posted by alexiskai

In my case, a leakdown test pinpointed #2 exhaust. I pulled the head and found that someone had put an undersized valve seat insert on it, which had come loose. Engines wear evenly, but humans make mistakes unevenly. Sometimes you're just correcting a mistake.

Humans makes mistakes, WHAT!