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Dec 30th, 2023
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 Compression Question
#15321104
02/02/25 11:59 PM
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Joined: Oct 2002
Posts: 4,104
mjmetro0719
OP
TFF Team Angler
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OP
TFF Team Angler
Joined: Oct 2002
Posts: 4,104 |
Need some advice from some mechanics if you don’t mind. I’m looking to put another engine on a 17’ center console and I have been looking at a used 1996 Mercury Tracker 90HP. The price is in the ballpark of what I’m willing to spend but the compression is reading 95 on all three cylinders. Is that to low of a compression or should I be concerned with it. Most engines I’ve had before were 110 and above. Any comments and advice are greatly appreciated.
Mike
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Re: Compression Question
[Re: mjmetro0719]
#15321120
02/03/25 12:20 AM
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Joined: Apr 2017
Posts: 14,517
tmd11111
TFF Guru
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TFF Guru
Joined: Apr 2017
Posts: 14,517 |
Was the motor up to temp or was it done cold. If up to temp I wouldn't be too concerned, actually would be ecstatic with all 3 the same. Could always check it against another gauge as not all read the same.
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Re: Compression Question
[Re: mjmetro0719]
#15321174
02/03/25 01:41 AM
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Joined: Jan 2005
Posts: 21,194
Pat Goff
TFF Guru
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TFF Guru
Joined: Jan 2005
Posts: 21,194 |
All the same?
You’re good.
That’s not a high compression motor but very reliable.
Pat Goff Seadrift TX ![[Linked Image]](https://i.ibb.co/X48Kbbq/scooter-shallow.jpg)
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Re: Compression Question
[Re: mjmetro0719]
#15322055
02/03/25 11:50 PM
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Joined: Aug 2016
Posts: 1,497
T-racer @ Mallard Marine
Extreme Angler
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Extreme Angler
Joined: Aug 2016
Posts: 1,497 |
I agree with what's posted above for the most part, but also wanted to add that we commonly see "low" compression evenly across the board like what you've posted above from lesser quality gauges. Particularly harbor freight. I can't tell you how many customers call wanting a rebuild because they have 70 pounds per hole of compression and they show up and they have 120 on every hole on a quality snap on or matco gauge we use. We send them home with a good chuckle.
Mallard Marine Nacogdoches, Tx
936-225-3244 - Authorized Sales/Service
Mercury Outboards - Allison Boats
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Re: Compression Question
[Re: T-racer @ Mallard Marine]
#15322066
02/04/25 12:13 AM
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Joined: Apr 2017
Posts: 14,517
tmd11111
TFF Guru
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TFF Guru
Joined: Apr 2017
Posts: 14,517 |
I agree with what's posted above for the most part, but also wanted to add that we commonly see "low" compression evenly across the board like what you've posted above from lesser quality gauges. Particularly harbor freight. I can't tell you how many customers call wanting a rebuild because they have 70 pounds per hole of compression and they show up and they have 120 on every hole on a quality snap on or matco gauge we use. We send them home with a good chuckle. Funny as 70psi isn't even enough compression to ignite the fuel
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Re: Compression Question
[Re: mjmetro0719]
#15322522
02/04/25 04:03 PM
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Joined: Jan 2005
Posts: 21,194
Pat Goff
TFF Guru
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TFF Guru
Joined: Jan 2005
Posts: 21,194 |
Do a proper two can mercury power tune treatment to it, and watch the compression go up.
Pat Goff Seadrift TX
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Re: Compression Question
[Re: mjmetro0719]
#15322943
02/05/25 12:19 AM
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Joined: Oct 2002
Posts: 4,104
mjmetro0719
OP
TFF Team Angler
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OP
TFF Team Angler
Joined: Oct 2002
Posts: 4,104 |
I appreciate all the advice. It makes me feel better that this engine might work for me.
Mike
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