Blackmax 150 xr2 or xr4 ?

[rustyjeep]

Hello everyone, long time lurker first time poster. I just acquired a 150 black max. How do I tell if its a 2.0 or 2.4 My ser# is ob265116 and I looked at max rules and I cant determine what I have.The numbers below are copied from max rules.

150 1988 ELPTO B241881 - C100860
150 1988 EXLPTO B241881 - C100860
150 1988 ELPTO XR4 B242885 - C100860

 

[Faztbullet]

Re: Blackmax 150 xr2 or xr4 ?

If cowling just has 150 Black max its a 2.0L, If it has Xr2 its a 2.0L if its says Xr4 its a 2.4L. Quickest and easy way to tell is look on cylinder head casting as it will have 3-1/8 (2.0L) or 3-3/8 (2.4L) cast into the side of it.

 

[Dukedog]

Re: Blackmax 150 xr2 or xr4 ?

One other thing. If its "unmolested" and no XR badge on tha cowl its gonna be a 2.0 motor................

 

[rustyjeep]

Re: Blackmax 150 xr2 or xr4 ?

Thanks for the help guys. I think mine has been "molested" I looked on the heads and it has 3 3/8 cast into it. My cowling just says 150 black max. It also has the big lower unit I think? I am still trying to determine that.

 

[rustyjeep]

Re: Blackmax 150 xr2 or xr4 ?

One other thing I was thinking, could I have a 175 re badged as a 150? How can I tell?

 

[rustyjeep]

Re: Blackmax 150 xr2 or xr4 ?

Well just a little update: I looked at the freeze plug on top of the power head and it is stamped 200. So does this mean its a 200 block re-badged as a 150?

 

[Dukedog]

Re: Blackmax 150 xr2 or xr4 ?

Vertical reeds, 175. Horizontal reeds, 200. Or if its clam shell cowls and has tha two steel hook type latches with springs, 175. If it has single interlocking plastic latch, 200. Thats tha 2 easy ways ta tell............This is only if it has an air box on tha carbs. No box both types will fit either one.

 

[rustyjeep]

Re: Blackmax 150 xr2 or xr4 ?

Its got clam shell cowls with two hook style latches, and it has an air box. Is the 200 stamped on the freeze plug an old wise tale?

 

[Dukedog]

Re: Blackmax 150 xr2 or xr4 ?

No wise tale. Its a 175. They use a 200 block half with a vertical reed front half ta get tha 175 rating. They can run real close to a 200. Sometimes better than some 200's...............

 

[Fun Times]

Re: Blackmax 150 xr2 or xr4 ?

This may not mean a whole lot if the engine has been molested, But for what it's worth, this engine serial number started life out as an 1988 MERCURY 2.0L 150 H.P L (V-6) Model No: 1150412BD

 

[Dukedog]

Re: Blackmax 150 xr2 or xr4 ?

If that whats on tha clamp Bracket it don't mean nothin' as for tha powerhead. If its got tha 200 stamped on tha welsh plug tha block half started out as 2.4 200 chrome bore. Now if it has been extensively "molested" from what your sayin' all tha 2.0 stuff with tha exception of tha pistons and rings "could" have been bolted up tha tha 200 block. Including tha 2.0/150 front crankcase half. One give away for that would be to look for a wh number on top of tha carburators. But I seriously doubt thats whats happened. Mainly because it has tha 3 3/8 stamped on tha heads.................Probably just a PH swap.

With 3 3/8 stamped on tha head translates to a 2.4 Tha heads could have come from either a 200 or tha xr4. those two and tha 175 were tha only 2.4's built. Tha xr4 being a "steel" sleeve 2.4 motor. Those heads will bolt up to a 2.0 motor but with tha 200 stamp that says 200 chrome bore 2.4 block................

 

[rustyjeep]

Re: Blackmax 150 xr2 or xr4 ?

That makes since! I will look at the carbs tomorrow and see what they are. Thanks so much for everyone help thus far. I am sure I will have many more questions as I get this thing running.

 

[rustyjeep]

Re: Blackmax 150 xr2 or xr4 ?

OK I took the air box off and got the carb #: WH-34-1,2,3 respectively. Also it had 1976 stamped above the others? On the middle carb the gold plate on top has 155 & 157 stamped in it. It was the only one I could see without further dis-assembly.

 

[Dukedog]

Re: Blackmax 150 xr2 or xr4 ?

Ya got me. I've never seen a 34 but that don't mean a thing. Something that Merc has made a lot harder than seems necessay is their method of identifing and an abundance of carbs for tha V6. Usually not enough information. Some may show on some charts and not on others and vica versa! I've got a few charts "somewhere". Maybe I can find 'em. But I'm still bettin' on tha 175 thing........

 

[Faztbullet]

Re: Blackmax 150 xr2 or xr4 ?

WH-34 are 175 hp carbs, and they did have some chrome bore 175's in 87-88....

 

[rustyjeep]

Re: Blackmax 150 xr2 or xr4 ?

I'm gonna pull the heads tomorrow. I really appreciate all of yall's help trying to get this thing figured out.

 

[Dukedog]

Re: Blackmax 150 xr2 or xr4 ?

Just remember this. There are probably VERY few all chrome bore motors still out there. Most are replaced with a "steel sleeve" if they go down. You may find one or more clyinders done this way. Not hard ta tell tha difference when ya open it up. But I can say with certainty that with tha "200" stamp it left Merc as a all chrome bore block half. Tha 175's use that block half with vertical front, different carbs, tuner and sometimes heads to get tha 175 badge..............Think '89 they went to a steel sleeve block which was basically tha XR4 block.........This is really testin' these old brain cells now!

 

[rustyjeep]

Re: Blackmax 150 xr2 or xr4 ?

As expected yall were right. It is a chrome bore block,except for #3 it has been sleeved.There is hardly any carbon on the pistons and you can still see the cross hatch pattern on the sleeved cyl. I dont think this motor has been ran much since it was rebuilt. I dont know any history on this motor other than it has been sitting for 10 years. I'm gonna rebuild the carbs and the fuel pump, new stats and poppet and impeller and see if it will go bang. I checked the compression and they are all around 110 except the one thats sleeved and its at 103? Dont know what thats about but I think it should be OK. Is there anything else I should do to bring this motor back to life?

 

[Dukedog]

Re: Blackmax 150 xr2 or xr4 ?

Mystery solved huh! Comp is a little low all tha way around but that could be tha guage. If you have access to another, try it. No Harbor Frieght or Northern! Did you pull ALL tha plugs doin' tha comp test? Squirt a little mixed oil/fuel in 'em (through tha carburators) and turn it over a bunch with plugs out. Check chrome for peeling and/or chips. Especially around tha ports and at tha bottom. They might have some (few) very small what will look like "pin" holes scattered around in tha clyinders. These will actually help with coolin' tha clyinder. If there are none, thats ok to. "New head gaskets". Try comp test again. Change tha complete water pump. Not just tha impeller..............