1973 evinrude 115 hp compression readings help

[antonio88]

hi i did a second time readings on the 1973 evinrude 115 hp it got overheated like 4 year ago and a friend of mine gave it to me, these are the correct readings

cil 1: 131
cil 2: 121
cil 3:150
cil 4: 152
i was wondering if these readings means if a have a good compression and a good motor?
thanks

 

[coolbri70]

Re: 1973 evinrude 115 hp compression readings help

cylinders 3 and 4 seem high, they should be closer to each other

 

[antonio88]

Re: 1973 evinrude 115 hp compression readings help

so da means is some wrong w it

 

[Joe Reeves]

Re: 1973 evinrude 115 hp compression readings help

You have 31 psi difference between the highest and lowest compression reading.

Remove the cylinder heads so that you can inspect the sealing surfaces of the head and block, and the gaskets themselves.

Hopefully the problem is sumply that the gaskets are faulty... OR the bolts are loose due to the severe overheating and have never been retorqued. Let us know what you find.

 

[antonio88]

Re: 1973 evinrude 115 hp compression readings help

ok ill remove the heads so it will be a good idea of replace the gaskets since im removing the heads i mean they can look ok but their faulty

 

[Joe Reeves]

Re: 1973 evinrude 115 hp compression readings help

Unless the head gaskets are new "and still look new", yes they should be replaced. The head bolts would need to be torqued down to 18 to 20 foot pounds in the following sequence where each number is a bolt.

9....10
5.....6
1.....2
4.....3
8.....7

However, before spending money on new gaskets, assuming that no bolts were loose, the gaskets were not burnt anywhere, the sealing surfaces were okay..... inspect that low psi reading cylinder closely for piston damage, scored cylinder walls, and broken or stuck piston rings.

 

[emdsapmgr]

Re: 1973 evinrude 115 hp compression readings help

Antonio88. You've got two threads going on this exact topic. You will find you get better answers if you keep all of them on one thread.

 

[racerone]

Re: 1973 evinrude 115 hp compression readings help

Take the bypass cover ( 6 bolts ) of the lowest reading cylinder.------It allows you to look at the piston and the rings.----May just require a new gasket for 99 cents.

 

[antonio88]

Re: 1973 evinrude 115 hp compression readings help

hello everyone so i changed the head gaskets, water jacket gaskets and new impeller and i got the motor to run i let run for like 10 min on idle so i went back to check the compression with the motor warm and a got different readings now

cil 1- 125
cil-2 121
cil-3 124
cil 4- 125

 

[Joe Reeves]

Re: 1973 evinrude 115 hp compression readings help

Good readings.

 

[emdsapmgr]

Re: 1973 evinrude 115 hp compression readings help

Agree with Joe. 125 would be normal for a factory new 1973 engine.