9.9 or 8hp outboard - cant find serial number plate

[Sailpower]

Hi, just picked up a tidy looking outboard motor which was supposed to be a 9.9 hp.. On collection its got an 8hp cowl on top, which may be a swap part for all I know? I can't see a serial number plate anywhere around the transom bracket or clamps. The only number I can find is on an engine core plug - 9590204 -

First - is there any way of identifying the serial number

Second - are there any distinguishing components which would confirm its an 8 or a 9.9? Its got mercury on the coils if that narrows it down at all!

 

[limitout]

Re: 9.9 or 8hp outboard - cant find serial number plate

if im not mistaken the flat spot next to the "tested OK" in the 4th picture should be your motors ID number or at least a number that helps you identify it.

as to the size, believe what you see. if it say 8hp then that's what you have and until you find proof otherwise don't assume the seller was honest with you about that.

look around the engine block and there should be the "CC" stamped on it somewhere telling you how many CC's the engine is and that is what will tell you the size.

also look closely at the carbs for an ID tag or its own "CC" number, that might be a clue to help ID things as well since sometimes the carbs change bores and CC's when motor size changes.

the trouble is, with small engines like this lots of times things are generic and fit 3 or 4 sizes of motors with only minor changes like carb jets

 

[Sailpower]

Re: 9.9 or 8hp outboard - cant find serial number plate

if im not mistaken the flat spot next to the "tested OK" in the 4th picture should be your motors ID number or at least a number that helps you identify it.

as to the size, believe what you see. if it say 8hp then that's what you have and until you find proof otherwise don't assume the seller was honest with you about that.

look around the engine block and there should be the "CC" stamped on it somewhere telling you how many CC's the engine is and that is what will tell you the size.

also look closely at the carbs for an ID tag or its own "CC" number, that might be a clue to help ID things as well since sometimes the carbs change bores and CC's when motor size changes.

the trouble is, with small engines like this lots of times things are generic and fit 3 or 4 sizes of motors with only minor changes like carb jets

I'll look for those things thanks. I don't suppose anyone might know if the red flywheel is significant? all others I've seen have been black!

Thanks again

 

[carholme]

Re: 9.9 or 8hp outboard - cant find serial number plate

Whether it is an 8 or 9.9, they would both be 1990 engines, made in Belgium.

9,9 9586000 - 9629999 1990

From here:

Mariner 9,8-20 hp, produktions?rslista, modellguide

8 09586000 - 09629999 1990

From here:

Mariner 2 - 8 hp, produktions?rslista, modellguide

Both engines use the same parts list:

6 / 8 HP 9.9 / 15 HP - Mercury, Mercruiser, Force, etc. Parts Lookup

The service manual you need for either engine is P/N: 90-827242R02 and if you do not have one, see my PM to you in Notifications at the top of the page.

Gerry

 

[Sailpower]

Re: 9.9 or 8hp outboard - cant find serial number plate

Thanks very much Gerry, I'll keep looking for a clue as to the capacity - if the cowls are model specific that might tell me its an 8 or 9.9 - the casting numbers don't seem to indicate anything at the moment.

 

[limitout]

Re: 9.9 or 8hp outboard - cant find serial number plate

make a call to a mariner dealer and ask where the number plate is, if your number plate has been removed then most likely it might be a stolen motor which might explain the wrong cowling to change its appearance.

if the motor is stolen there is no way to find the original owner since the tag is gone but at the very least the dealer should be able to give you a way to confirm what hp it is.

if you are ever checked on the water and they see the tag was removed then it will be an issue trying to explain where you got the motor so keep copies of the sale document on the boat with you at all times and for your sake I hope you got the guys drivers license number on the bill of sale

 

[steelespike]

Re: 9.9 or 8hp outboard - cant find serial number plate

delete

 

[steelespike]

Re: 9.9 or 8hp outboard - cant find serial number plate

Ok here goes 8hp 79-84 has a cylinder head w 13 head bolts,85-87 8 hp has no head but has a head cover w 7 bolts, 79-86 9.9 has head with 11 bolts.
88/89 8 and 9.9 have a E shaped block cover w 6 bolts,CH. L82YC w regular coils and NGK BUHW with high energy.
This is as best I can tell from an after market manual.
Probably not much help with the 88/89 8 and 9.9.

 

[Sailpower]

Re: 9.9 or 8hp outboard - cant find serial number plate

Thanks Steelspike,
I've bought the engine from our local sailing club who have had a clear out - I think the engine has been unused for 5 -6 years but has been owned by the club for around 10 years. I'll get a bill of sale from them. Because the documentation of the club is relatively basic and the engine is quite old, service records and proof of original purchase are difficult to find - no specific receipt that can be found - it is remembered as a 9.9 but no one can say why its got an 8 cowl on!

I think from the core plug number its a 1990 engine according to Carholme, maybe the best is to ask a dealer as you suggest to say what features a 9.9 would have. By the part numbers the 1990 cowls seem to be the same basic item for both models so could be swapped. I'll also look for images on line that might help.

Thanks again for your help, I'll keep the forum updated!

 

[ondarvr]

Re: 9.9 or 8hp outboard - cant find serial number plate

The 8 and 9.9 of that year share almost every part and are the same displacement, so the cowl would fit either one. You can look up the parts list on line and look for the exact differences, should only take a few minutes to find out which one it is.

 

[MH Hawker]

Re: 9.9 or 8hp outboard - cant find serial number plate

This should be the ser number

 

[Sailpower]

Re: 9.9 or 8hp outboard - cant find serial number plate

Hi Thanks MH Hawker, I agree, the number on the core plug dates the engine to 1990, Carholme helped and directed me to a site listing the serial number / model year. I'm thinking that the carb might be the best indicator of which model it is, 9.9 or 8hp

thanks for the advice!

 

[limitout]

Re: 9.9 or 8hp outboard - cant find serial number plate

glad you figured things out

 

[Sailpower]

Re: 9.9 or 8hp outboard - cant find serial number plate

Hi I spoke to a dealer today who couldn't really suggest any way of differentiating between a 9.9 and 8 hp, given that I only other than by the carb jets. The suggestion was that only the carb orifice /jets and venture diameter would be different - so a carb strip down should be the way to tell.
This might imply that a carb swap would change the HP?

 

[ondarvr]

Re: 9.9 or 8hp outboard - cant find serial number plate

If the carb is larger it will possibly have the model # stamped on the outside, so there may be no need to pull it appart. Just look up the parts list for each one online, some list the carb #s for each model. Again, it should only take a few minutes to find out.

 

[limitout]

Re: 9.9 or 8hp outboard - cant find serial number plate

Hi I spoke to a dealer today who couldn't really suggest any way of differentiating between a 9.9 and 8 hp, given that I only other than by the carb jets. The suggestion was that only the carb orifice /jets and venture diameter would be different - so a carb strip down should be the way to tell.

no need to strip it down because the carb should be stamped or have a tag saying the "cc" size which is the venture diameter he was talking about.

plus lets be honest, you aint going to really notice the difference THAT much so its not worth going to a lot of trouble over it. if I were you and I really really wanted to make sure it had the 9.9hp it had the ability to make then i would pull the carbs and check and if it was the small carb I would look on ebay to find the 9.9 carb as the cheapest way to get there.

This might imply that a carb swap would change the HP?

yes that is what he is saying, change the carbs changes the hp rating but don't try to do it just with swapping out with new jets because that always has issues running right. I have seen it too many times trying to "upgrade" the smaller carb.

 

[Sailpower]

Re: 9.9 or 8hp outboard - cant find serial number plate

Ok thanks , understood - I'll compare part numbers and see where the models differ I'll check pistons as an indicator of the bore diameter, connecting rods for the length of stroke, the reed valves and finally the carb, and see where the differences lie. Maybe I'll include the 15hp parts too! On te 95 Johnson/Evinrude I have the carb is the only difference between 9.9 and 15.

Thanks again, I know a whole lot more about the motor already.

 

[limitout]

Re: 9.9 or 8hp outboard - cant find serial number plate

Ok thanks , understood - I'll compare part numbers and see where the models differ I'll check pistons as an indicator of the bore diameter, connecting rods for the length of stroke, the reed valves and finally the carb, and see where the differences lie. Maybe I'll include the 15hp parts too! On te 95 Johnson/Evinrude I have the carb is the only difference between 9.9 and 15.

Thanks again, I know a whole lot more about the motor already.

yep, I know they used to do that with the 90hp & 115hp and the 125hp &135hp evinrudes too. they just put larger bigger carbs on them so if you had a 90hp you could buy a used carb for the 115 and your motor would be a 115hp and the same to go from 125hp to 135hp. its a common practice to save money by making the same parts fit many models.

now days with fuel injection and computer sensor controlled engines they don't do that anymore or at least its not as simple as all that.

 

[MH Hawker]

Re: 9.9 or 8hp outboard - cant find serial number plate

Ok thanks , understood - I'll compare part numbers and see where the models differ I'll check pistons as an indicator of the bore diameter, connecting rods for the length of stroke, the reed valves and finally the carb, and see where the differences lie. Maybe I'll include the 15hp parts too! On te 95 Johnson/Evinrude I have the carb is the only difference between 9.9 and 15.

Thanks again, I know a whole lot more about the motor already.

It really depends on what year it is, from 1995 to 2000 the 9.9 can be changed to a 15 but thats about the only ones that can with out extensive work, I did mine last year.

 

[ondarvr]

Re: 9.9 or 8hp outboard - cant find serial number plate

Up untill about 95' the 6, 8, and 9.9 were the same displacement, the 15 was larger. After 95' the 9.9 displacement was increased to be the same as the 15.

On the 90 and 115 J/Es there were more differences than just the carb to increase the HP.