TOPIC: What is a "snap" test.

As referenced in the ad in the glassifieds. I am in the process of getting (2) low hr but not cared for properly '59 Johnson 35hp engines. I want to do as much check out as possible before trying to firing these 2 up. Here is the ad I am referring to...

Melanie



Looking to either get the motor I have up to snuff, or replace it with a better '57 Evinrude 35 hp. I have the electric parts stuff, but if it comes with the motor, that would be GREAT! I think the powerheads between '57 and '59 will interchange. Of course looking for one with good compression readings and one that will pass the "snap" test on the rod bearings

I snapped a rod bolt in a Johnson 9.9 one time, that test didn't last long! Big hole in crankcase, big mess. Sorry Melanie, I'm clueless.

Here it is. With the spark plugs out, run the piston to up and over TDC. When the piston has gone down maybe 1/4 or 1/2 way down, take a screw driver, a pencil or what ever and carefully push on the piston top. If there is wore wrist pins, you will feel and hear a "click" or "snap". This is the slack being taken up as you push on the pistons. If it is a multi-cylinder engine, do each piston, to see if there is one wore more than the others. I am told there should be very little "snap". How much is very little? Good question, but the one I have sounds excessive to those that heard and felt it. Hope this makes sense, if not, let me know and I will try again.

Makes perfect sense DaveK, thanks! (Checking for play/excessive clearance in the wrist pin and/or rod bearing.)

Oceans2 wrote:

I think the powerheads between '57 and '59 will interchange.

They will not. 1957 was the last year of the single-wall mid-section 35 as the only model available. 1958 had both the single-wall model and the double-wall (silent package) models. 1959 had only the double wall models available.

The single-wall 1957 and 1958 models share pretty much all parts. A single-wall and double-wall motor share about 60% of the parts. Pretty much all moving parts are the same (crankshafts, rods, pistons, etc.). Most all of the non-moving parts are different (cylinder block, head, carb, shrouding, lower housings, etc.) Some exceptions to either rule, but you get the idea. Easiest way to tell the motors apart is the double wall motors from that era will have a bucket cowling. The single wall motors have a clamshell cowling.

- Scott

Thank you Dave for the explanation and I'd like to point out that the issue Chinewalker spoke to was was taken from the ad and not a statement by me.

Scott, so the 58 "Lark" model and all '59's would be different and would be the double wall model. Is that correct? I am always learning so I am always asking. I myself am looking for the single wall model. Just love that Evinrude blue.

Hi Dave,
That is correct. The '58 and '59 Lark models are the double-wall mids with bucket cowls. In 1958 the Big Twin 35 model was a single-wall mid/clamshell cowl. The 1959 Big Twin 35 was a double-wall mid/bucket cowl (all blue, with gold and white accents). It took them two model years to phase out the single wall model and phase in the double wall.
A little easier with Johnson... They had the transition year in 1958 with both single and double wall models offered (standard bronze & white Sea Horse 35 with the single wall and the gold/white Super Seahorse with the double), but only one model offered in 1959 as the all white Super Seahorse 35 with the double wall.
- Scott

1958 Johnson Sea Horse 35 with single wall mid and clamshell cowling.


1959 Johnson Super Sea Horse 35 with double wall mid and bucket cowling.

Well, for what it is worth. My WTB ad paid off and I have what sure appears to be a very engine now in my workshop. Though the motor was in cold storage, the seller did the snap test for me and found no play at all. I drove 250 mi. then to get it. I also performed the snap test on this cold motor and found no play, but was concerned, that the oil and everything else being cold, may be masking the problem. By the time I got home, the motor was in the car and warm. In the workshop last night, I checked it again. This motor has no play what so ever. It is like pushing on a wall. The compression is good, though being a manual start 35, it is hard to get it spinning hard enough to really get it to pump up as it would with electric start. But, so far I am as happy as a clam. I think I found a '57 35 Evinrude, that is as low mileage as can be found. I see many hours on the water with this motor pushing me.