Compression numbers ? (1 Viewer)

[lawdawg]

Looking at a 40 out of state, compression numbers came back below. I believe spec was 150, but over 105 is okay? My main question is I read in some of the other threads they should be within 10%. Any feedback appreciated on #2 and the results.

1: 125
2: 105
3: 120
4: 118
5: 118
6: 115

 

[SW20]

I don't think so. That is roughly 1/3 loss in that cylinder. I would even go to say that your highest cyliunder compression at 125 is on the low side.

 

[Jdc1]

Mechanicals are more straightforward than rust repair and paint/body. If it's complete and clean for the right price it could still be a decent buy. Have any pics?

 

[65swb45]

F or 2F?

Edit. This isn't that same rig you called me about two weeks ago, is it?

 

[SteveH]

For sea level elevation, those are a bit low. #2 could be a scored cylinder wall, or a bad valve or two. Or both.

 

[lawdawg]

F or 2F?

Edit. This isn't that same rig you called me about two weeks ago, is it?

No, couldn't reach him, different one

 

[lawdawg]

Mechanicals are more straightforward than rust repair and paint/body. If it's complete and clean for the right price it could still be a decent buy. Have any pics?

It's a good looking truck, little rust on sill and corners which wS cut out and new metal put in, but thinking of driving it back over 1,500 miles if I like it and just worried about the engine.

 

[Jdc1]

It's a good looking truck, little rust on sill and corners which wS cut out and new metal put in, but thinking of driving it back over 1,500 miles if I like it and just worried about the engine.

View attachment 1390202

You'll want to see it in person and worse case scenario you put it on trailer for the trip home. The compression results are definitely a bargaining tool.

 

[65swb45]

water on the ground and a box fan stuffed into the engine bay. Priceless.

 

[tls3601]

Nice looking truck

 

[dunebeigefj40]

That is definitely an aftermarket carb cooling fan they have installed, you may want to go back to original on that

 

[emac]

I agree with @Jdc1: Complete vehicle, body, rust, unmolested wiring/interior outweighs a motor/driveline rebuild. I see you are in Atlanta, I am in upstate SC and check Craigslist often. It seems there are only 35K trucks that look very good or 10K trucks that are complete garbage. I havent seen any honest used 40's in a long time around here.

If it looks decent and the price is a little more than you want to pay, then buy it! Good luck, keep us posted!

 

[GHalll]

It's a good looking truck, little rust on sill and corners which wS cut out and new metal put in, but thinking of driving it back over 1,500 miles if I like it and just worried about the engine.

View attachment 1390202

Trailer it home..

 

[Graniteone]

If these compression numbers are your only worry then you should not be to concerned. I drove 1500 miles on very similar compression numbers with no issue at all. Live a little!

 

[TractorDoc]

Cool truck. . . judging by the tape on the front and rear doors you should at least have new weather stripping to keep the elements out if you drive it home!

 

[sggoat]

That is definitely an aftermarket carb cooling fan they have installed, you may want to go back to original on that

Very good!!
I think it's just there to hold the hood--the support rod appears mia

 

[emac]

I cant imagine 1500 miles in the 40!

 

[thebigredrocker]

@65swb45 sorry to pester you

if a compression test is done on F/2F with both Aisan throttle plates closed would that result in lower compression test numbers as opposed to comp testing with WOT during engine cranking?

Also, "could" a test with all spark plugs removed show different results than testing each cylinder with spark plugs installed in the remaining 5 cylinders?

Should the fuel be shutoff to prevent unburnt gas from washing oil from the pistons?

@lawdawg Do you know if they've done a proper valve adjustment lately? If you are going to buy it, might not hurt to bring a feeler gauge and see if they'll let you pop the valve cover. That might shed light on why #2 is low.

I also think it's wise to crack open the tranny fill plug, to see if water gushes out. If it does, it wouldn't be a deal breaker for me. Just another negotiating tool.