Compression on 1994 Evinrude?

[Boat4Life]

I have a 1994 Evinrude 150 hp and it starts and runs fantastic. The other day while doing normal outboard maint.....inspecting spark plugs, changing lu lube, etc., I decide to check the compression while the plugs were out. All six cylinders registered 80-82 psi, so I figure I have a bad compression gauge or I need to decarb the engine. Like I said, it runs great. I'm thinking I will just buy a new gauge and check it again and regardless of the compression numbers the second time, just do a decarb anyway. What do you guys think?

[316jughead]

With the compressions so close to the same, I also would suspect the guage. I always found compression to be around 95 pounds. No harm in a decarb.

[meatballs9]

FACT: as long as all 6 cycl. are with-in 10psi of each other your all set! I have seen these motors out of the box NEW dont run at 95psi, so 85-82 on all 6 no worries, change plugs,lower unit oil,fuel filter, FRESH gas= great day on water keep fishing!

[316jughead]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by meatballs9 &raquo;</td></tr><tr><td class="quote">FACT: as long as all 6 cycl. are with-in 10psi of each other your all set! I have seen these motors out of the box NEW dont run at 95psi, so 85-82 on all 6 no worries, change plugs,lower unit oil,fuel filter, FRESH gas= great day on water keep fishing! </td></tr></table>

Fact: The compression readings stated were 80 to 82, which are all with in the 10% to 15%, And they are low, that is why we suspect the guage. I never checked the compression on a, new out of the box, Intruder, however I do have a very accurate guage and the ones I did check, were all 92 to 95 or so pounds. There are a lot of variables in a compresion test on a two stroke, when in doubt I did a leak down test. I was wondering how many, new out of the box, Intruder motors you did a compression test on.

[Melton Jason]

I think technically you are supposed to have the throttle all the way open too and squirt a bit of 2 stroke oil down inside. Did you do that?

Reason I ask, I tried it a couple different ways when I was checking mine the other day and it would be almost 10lbs higher on each cylinder. Between having the throttle bodies open versus closed.

[316jughead]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Melton Muskie &raquo;</td></tr><tr><td class="quote">I think technically you are supposed to have the throttle all the way open too and squirt a bit of 2 stroke oil down inside. Did you do that?

Reason I ask, I tried it a couple different ways when I was checking mine the other day and it would be almost 10lbs higher on each cylinder. Between having the throttle bodies open versus closed.</td></tr></table>

Yes, throttle open.

[Bassmeister]

Shouldn't the engine be warmed up also??

[316jughead]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Bassmeister &raquo;</td></tr><tr><td class="quote">Shouldn't the engine be warmed up also??</td></tr></table><table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Bassmeister &raquo;</td></tr><tr><td class="quote">Shouldn't the engine be warmed up also??</td></tr></table>

Well, yes it probably should, but I suspect that most compression checks are done cold.

[Boat4Life]

Thanks for the helpful replies! I am going to try it with a borrowed gauge and compare to my gauge readings. When I checked it, I did not have the throttle wide open and the engine was not warmed up. I can't complain about how the engine runs. It starts, idles and runs great. Just a little surprised by the compression readings. My thinking is that if I can do something such as decarbon, etc., to help, then that might extend the life of the engine. This is assuming the compression is a little low on all cyclinders.

[316jughead]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Boat4Life &raquo;</td></tr><tr><td class="quote">Thanks for the helpful replies! I am going to try it with a borrowed gauge and compare to my gauge readings. When I checked it, I did not have the throttle wide open and the engine was not warmed up. I can't complain about how the engine runs. It starts, idles and runs great. Just a little surprised by the compression readings. My thinking is that if I can do something such as decarbon, etc., to help, then that might extend the life of the engine. This is assuming the compression is a little low on all cyclinders.</td></tr></table>

You should decarb once a year anyway. Use Evinrude XD30 oil, if your not going to use the boat for a while, such as winter, use fogging oil and fuel stabilizer. I always checked compression cold, if I suspected a problem I would check warm or do a leak down test. Have a great time.

[meatballs9]

My comment was not meant to affined anyone, could be his gauge. However all 6 cylinders are wearing evenly. As you stated they are with in 10-15 psi. This is most important, If #1 cylinder on portside reads 83 and #5 cylinder reads 62, you'd have a issue, this gentleman doesn't have that problem. I have owned nothing but Evinrudes thus far, doesn't make me an expert, I was just tryn to help the gentleman out. I have been told by my mechanic which has worked on Evinrude 150 for years, that even wear is what your looking for. For example when I did my compression check all 6 read 100psi, I asked the exact same question seems low to me, his reply was what I just stated. GO SOX!

[316jughead]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by meatballs9 &raquo;</td></tr><tr><td class="quote">My comment was not meant to affined anyone, could be his gauge. However all 6 cylinders are wearing evenly. As you stated they are with in 10-15 psi. This is most important, If #1 cylinder on portside reads 83 and #5 cylinder reads 62, you'd have a issue, this gentleman doesn't have that problem. I have owned nothing but Evinrudes thus far, doesn't make me an expert, I was just tryn to help the gentleman out. I have been told by my mechanic which has worked on Evinrude 150 for years, that even wear is what your looking for. For example when I did my compression check all 6 read 100psi, I asked the exact same question seems low to me, his reply was what I just stated. GO SOX!</td></tr></table>

OK, no problem, welcome to the forum. I also have personaly owned nothing but Evinrudes. I also have worked on 150's from the first ones thru 1995 when I retired. I loved working on motors so much that when I bought the dealership I remained the service manager.

[Bassmeister]

All good here, jughead, I respect all you do here and your knowlege!!