Powerhead interchangeability

[vwbjohn]

I bought a 1989 Mercury 135 black max (serial#C166987). It has compression in 5 cylinders from 100-110 but one cylinder is dead. I’m currently soaking the cylinder in seafoam to see if I can get the rings unstuck. I’ve been told by several mechanics that I’m going to need to rebuild the powerhead. Are there any other year powerhead that are interchangeable. I’ve been looking on the internet and am not seeing any for 89 but several for 91-2001. I appreciate any advice where to get a rebuild or even a good used one. Thanks, John

 

[Faztbullet]

Rings only stick on a V-6 after cylinder is damaged. Quit wasting yer time and pull head..

 

[vwbjohn]

Rings only stick on a V-6 after cylinder is damaged. Quit wasting yer time and pull head..

We’ll as much as I’d like to thank you for your comment, it didn’t do anything for me. I think I know what I need to do but it doesn’t hurt to try some a less expensive method. I use seafoam in my cars so no expense wasted. Now if you can tell me if any other year powerhead will fit vice 1989, please let me know otherwise go tell someone else how stupid they are.

 

[jbcurt00]

@vwbjohn Fazt can be an excellent resource, but not if his advice is disregarded. His advice was brief but likely accurate. I dont see that he called you stupid.

 

[QBhoy]

We’ll as much as I’d like to thank you for your comment, it didn’t do anything for me. I think I know what I need to do but it doesn’t hurt to try some a less expensive method. I use seafoam in my cars so no expense wasted. Now if you can tell me if any other year powerhead will fit vice 1989, please let me know otherwise go tell someone else how stupid they are.

Seafoam has its uses. But it can’t fix a toasted cylinder or cylinder head. Good as it is. If you’re hoping it’s going to unstick a stuck ring…it might…but very few singular stuck rings, result in zero compression. Blown heads do though.

 

[vwbjohn]

@vwbjohn Fazt can be an excellent resource, but not if his advice is disregarded. His advice was brief but likely accurate. I dont see that he called you stupid.

If you read my original message, I was already considering a new/rebuilt powerhead. How can trying something in the interim be “wasting my time”? I obviously wasn’t disregarding his advise, I guess it was the way he worded it. I’d still like his advice on optional powerheads if he has one.

 

[Faztbullet]

Pre 1991 2L 135/150 will fit. After 1991 they went to fat block casting like 2.5L. These will also fit but have to get whole assy as heads,exhaust plates different

 

[Dukedog]

thats jus a "brutal way" of tellin' ya ya gettin' some lame advice from somewhere.. unless ya come up with it on ya own.. faz, ya outta be ashamed )
jus a coupla questions?.. ya looking for a complete, runnin' powerhead or justa "long block" type deal.. they will all (2.0. 2.4, 2.5's) bolt up.. tha one thing that will stand out is exhaust openin' from block but that can be worked around..
mainly "outside parts" can/will be different..... your stuff will only work on '90 down, 150 hp and less.. (mainly reg/rectifier, divider plate if its tha water cooled 40)..

 

[vwbjohn]

Pre 1991 2L 135/150 will fit. After 1991 they went to fat block casting like 2.5L. These will also fit but have to get whole assy as heads,exhaust plates different

Thanks. Sorry for being a JA in my previous response. I’m not an outboard mechanic, just thought trying some tricks I’ve used on cars might work. So The 1991 will bolt right up? I’ve seen several remand for sale so I’ll check them out. Thanks again for your help. John

 

[vwbjohn]

thats jus a "brutal way" of tellin' ya ya gettin' some lame advice from somewhere.. unless ya come up with it on ya own.. faz, ya outta be ashamed )
jus a coupla questions?.. ya looking for a complete, runnin' powerhead or justa "long block" type deal.. they will all (2.0. 2.4, 2.5's) bolt up.. tha one thing that will stand out is exhaust openin' from block but that can be worked around..
mainly "outside parts" can/will be different..... your stuff will only work on '90 down, 150 hp and less.. (mainly reg/rectifier, divider plate if its tha water cooled 40)..

Sounds good. Fatz was saying 1991 powerhead would work as well. You mentioned 150, would there be any issues putting a 150 powerhead in place of the 135 on my motor? I understand it would give me more power but would the rest of the motor take it? Are the 150’s just a different bore and stroke or are carbs different as well? Really appreciate the help.

 

[444]

Sounds good. Fatz was saying 1991 powerhead would work as well. You mentioned 150, would there be any issues putting a 150 powerhead in place of the 135 on my motor? I understand it would give me more power but would the rest of the motor take it? Are the 150’s just a different bore and stroke or are carbs different as well? Really appreciate the help.

Mercury often used the same short block with different carbs or reeds/intake to achieve different HP numbers.

 

[vwbjohn]

Mercury often used the same short block with different carbs or reeds/intake to achieve different HP numbers.

Great. Gives me a few more options when looking for a replacement powerhead. Thanks for the info.

 

[Dukedog]

Sounds good. Fatz was saying 1991 powerhead would work as well. You mentioned 150, would there be any issues putting a 150 powerhead in place of the 135 on my motor? I understand it would give me more power but would the rest of the motor take it? Are the 150’s just a different bore and stroke or are carbs different as well? Really appreciate the help.

tha '91 and up is a different block like faz says.. tha three main differences (All hp's) in tha '90 down and tha '91 up are tha block, heads and exhaust divider plate.. those parts will not interchange.. i've run '91 up blocks on tha "2.0' liter" (135/150 hp) 90' model down (your motor) adapter plates also without any problems.. there is no concern about "tha rest of tha motor strength".. they are all tha same................