Mercury 40 ML 4SEF SN 1C056105

[diegomzt]

Hi im looking for opinions, a guy is selling me a mercury 40hp 4 stroke outboard, he said the motor its been sitting for about 6 months and now is not runing, spark is not strong enough and compression is:
1- 149 psi
2- 90 psi
3- 90 psi.

He is asking for 200 usd, could this compression differences being caused by the time it had been sitting? Or you think its something bad going on with valves, pistons heads ??

The motor was used for low level comercial saltwater fishing (panga). And he said the motor was runing great before, of course hes gonna say that haha!.

What you think?

 

[Fun Times]

Do you happen to know if the engine was ran/warm when tested or cold from sitting? as that may play a part in the reading numbers...Also open the throttle all the way open to test tends to help bit.

To locate the weaker compression test, you'd want to perform a cylinder leak down test next to try and see where the engine is losing it from.

You'd benefit from having the correct service manual on hand too which is Merc part number 90-899974, https://www.ebay.com/sch/i.html?_nk...id=p2334524.m570.l1313&_odkw=899974&_osacat=0

Here's your parts catalog to that serial number too to help get an idea of what it may cost to repair the area you find the issue to be,

Mariner Outboard 2006 40 [ML 4] 7F40213ZZ [7F40213ZZ] - Parts Lookup | Crowley Marine

View parts diagrams and shop online for 7F40213ZZ : Mariner Outboard 2006 40 [ML 4] 7F40213ZZ. Offering discount prices on OEM parts for over 50 years. FAST $4.95 shipping available.

www.crowleymarine.com

 

[diegomzt]

Do you happen to know if the engine was ran/warm when tested or cold from sitting? as that may play a part in the reading numbers...Also open the throttle all the way open to test tends to help bit.

To locate the weaker compression test, you'd want to perform a cylinder leak down test next to try and see where the engine is losing it from.

You'd benefit from having the correct service manual on hand too which is Merc part number 90-899974, https://www.ebay.com/sch/i.html?_nk...id=p2334524.m570.l1313&_odkw=899974&_osacat=0

Here's your parts catalog to that serial number too to help get an idea of what it may cost to repair the area you find the issue to be,

Mariner Outboard 2006 40 [ML 4] 7F40213ZZ [7F40213ZZ] - Parts Lookup | Crowley Marine

View parts diagrams and shop online for 7F40213ZZ : Mariner Outboard 2006 40 [ML 4] 7F40213ZZ. Offering discount prices on OEM parts for over 50 years. FAST $4.95 shipping available.

www.crowleymarine.com

The motor was cold when i did the test.

Thanks for the info !