Should I run it?

[mogfisher]

Hello. This is a new to me 89 Blackmax 150xr4. When I bought the boat I didn't bring my compression tester with me because I didn't think it worked. It's a really cheap POS but I tinkered with it and it does work.

I dont' trust the accuracy of the numbers, but I believe the consistency between cylinders should be relatively reliable. The top starboard cyl is slightly lower than the other 6. All the others read around 100 but this one only went to 80. The gauge doesn't even rest at 0 so like i said, I don't trust the actual numbers but from what I hear consistency is more important anyway.

My question is, should I run it or build it? I'm telling myself it's a stuck ring because that's what I want to believe and a decarb will take care of it. The motor has been sitting for a couple of years minimum. I wont be terribly heartbroken if the answer is rebuild it, but I really wanted to fish this boat this year and I know I won't have time to rebuild it myself in time and I like to do my own work. It's not the money that hurts, its the time.

My thoughts were to get it on the water with a tow boat if necessary and a can of sea foam and do a good decarb and see if the numbers change.

I've not built a boat engine, but done many cars and the basics seem the same. I have all tools necessary unless there are some special tools.

I bought this boat super cheap as a project because I just love taking old things and making them new, I was just hoping to enjoy it a bit this year first. So what advice can you give? Thanks!

Adam

 

[scoyt]

Re: Should I run it?

I had a 150 Merc that the top starboard side piston melted and came apart while going about 40 MPH, so I can tell you that it is a sickening sound when you are going down the lake, and all of a sudden, nothing! Make sure your trolling motor battery is fully charged, and give it a whirl! Get a new compression checker when possible, and go fishing!

 

[j_martin]

Re: Should I run it?

If it were mine...........
I'd look up the decarbing procedure in the faqs on this board, and do it. Basically you mix up a gallon of fuel in a pony tank and add a lot of seafoam to it, then run it through the engine at fast idle. Watch the wind direction and hanging laundry. This procedure can be rough on the neighbors.

Break down and buy a decent compression tester. Maybe you can rent one at the local Clown Auto.

hope it helps
john

 

[mogfisher]

Re: Should I run it? Update on my XR4

Re: Should I run it? Update on my XR4

Well, tonight my curiosity got the best of me and I pulled the heads. The boat wont be seaworthy for a while anyway, so I figured what the heck. I found the port side and both bottom cylinders on the starboard side were immaculate. No visible scoring fore and aft at all. Not even that much carbon. The cylinder in question with the low compression was a bit different. In 2 different spots there was noticable scoring of the cylinder and some aluminum deposits on the wall. Not a ton, but enough to lower compression. I actually think most of what I see is aluminum deposits and not scoring. I know this is bad but how bad? What further damage would I do by running this motor until fall? I'm not afraid of a rebuild but I want to fish this boat once it's ready. (doing a total hull restoration)

Another interesting point was that combustion chamber on the head on the bottom cyl on the starboard side was noticably cleaner than the rest but the piston was not. The piston had the same amount of carbon as the rest of the pistons but the head was super clean. Any ideas on that? At first I thought head gasket but wouldnt the piston be clean too? This puzzles me.

 

[sschefer]

Re: Should I run it?

It sounds to me like the engine was run under propped and over rev'd. That's usually what scores the cylinders that you're seeing problems with. #6 will often have a clean head but nobody can really explain why. Some say because of it's location others say jetting but I've never seen a really good answer.

The bad news is that you should not run it. Those deposits are aluminum and if you caught it early enough you can hone it with a Goodson or Sunen Mobile hone and it'll be good to go. You can't hone it with one of the autoparts store flex hones because it will end up out of round and you'll have blowby and wheezing.

I would recommend boring .015 over and replacing all the pistons but you can do an economy rebuild now and just fix what's really bad. Then fish it this season and do a full rebuild this winter. It will take you about 3 weeks of nights and weekends to get it done if you order parts in advance and about 1200.00 or less if you reuse your bearings and such.

The first thing you need to order is the Merc Service Manual.. Your work will go much faster if you use that instead of the Seloc or Clymer manuals.

Theres a bunch of us with extensive experience on these motors so ask your questions the minute you have them and we'll do our best to keep you on track.

 

[4JawChuck]

Re: Should I run it?

You have a leaking ring in that poor cylinder and it stuck the piston at some point, if you continue running it in that condition you risk total failure...as in rod out the side of the block type failure.

Take it apart and fix it properly, it will be worthless once the rod comes out the side. Consider yourself lucky you found the issue before running it, this is why a compression test is a good idea every year...never know what your going to find.

 

[mogfisher]

Re: Should I run it?

That's sad news but really is what I was expecting. I already have the OEM Merc manual so i'm good there.

Sschafer, what do you mean by economy rebuild? And the 1200 bucks is mainly for all 6 pistons, gaskets, and machine shop work, right?

From what I've read you can bore 1 cyl over and leave the rest. Is that really OK? The merc manual says that can be done. Since the rest of the cylinders look so good I was hoping I could just do that.

I don't believe in doing anything half way. I take "while I'm in there" to a new level sometimes. Is reusing bearings commonly done and OK to do? I'm sure my manual gives a way to check them, but in a true rebuild wouldn't they be replaced automatically?

I'll try to see if my camera can get me a good pic of the cylinder so I can show you guys. I'm very hopeful that I can just hone this cylinder and remove the aluminum without boring. I'm going to assume that I need a new cyl since the aluminum had to come from somewhere!

Is a rebuild on these motors that difficult? I've never worked on one before. Mechanically I'm pretty good. 4 years ago I did a full rebuild on an Audi 20valve turbo motor and transplanted that into my 92 Vw GTI. That car is still goes like stink so I cant be all bad. Seems that these boat motors are much simpler. It's just the fear of the unknown, ya know? The OEM manual and knowing I have the support of you fine folks make me feel a lot better.

It doesn't look good for getting this boat on the water this year. I've just split the cap to replace floors and foam. I also need to redo all the electrical. Now add a motor rebuild to it and the only way I'd get it in the water is to not go fishing at all this year! That wont happen. At least I have another boat to fish from.

 

[mogfisher]

Re: Should I run it?

One more thing to note. The PO said that the boat would not pump water after he took it out of storage. He SAYS he never ran it like that but we know how the word of a seller can be. There do seem to be signs of an overheat such as brittle insulation on the wire right at the head for the temp alarm switch. I assume that could have something to do with the unhappy cly #1. I did not verify that it would or would not pump water as the boat was not seaworthy when I bought it and I never tried muffs. I did start this motor dry ( I was counting on a complete water pump replace anyway) for less than a minute just to make sure it ran at all.

 

[CharlieB]

Re: Should I run it?

Once you pull that piston out you can clean the aluminum off the cyl with muratic acid. Once the cyl is clean run a quick pass with straight stone hone to freshen the finish and mic it, compare to the service limits in the OEM Manual. Only then can you make an informed decision whether you can replace the piston with a standard or have to bore it.

 

[sschefer]

Re: Should I run it?

That's sad news but really is what I was expecting. I already have the OEM Merc manual so i'm good there.

Sschafer, what do you mean by economy rebuild? And the 1200 bucks is mainly for all 6 pistons, gaskets, and machine shop work, right?

From what I've read you can bore 1 cyl over and leave the rest. Is that really OK? The merc manual says that can be done. Since the rest of the cylinders look so good I was hoping I could just do that.

I don't believe in doing anything half way. I take "while I'm in there" to a new level sometimes. Is reusing bearings commonly done and OK to do? I'm sure my manual gives a way to check them, but in a true rebuild wouldn't they be replaced automatically?

I'll try to see if my camera can get me a good pic of the cylinder so I can show you guys. I'm very hopeful that I can just hone this cylinder and remove the aluminum without boring. I'm going to assume that I need a new cyl since the aluminum had to come from somewhere!

Is a rebuild on these motors that difficult? I've never worked on one before. Mechanically I'm pretty good. 4 years ago I did a full rebuild on an Audi 20valve turbo motor and transplanted that into my 92 Vw GTI. That car is still goes like stink so I cant be all bad. Seems that these boat motors are much simpler. It's just the fear of the unknown, ya know? The OEM manual and knowing I have the support of you fine folks make me feel a lot better.

It doesn't look good for getting this boat on the water this year. I've just split the cap to replace floors and foam. I also need to redo all the electrical. Now add a motor rebuild to it and the only way I'd get it in the water is to not go fishing at all this year! That wont happen. At least I have another boat to fish from.

The econo rebuild is just fixing what's broke for now. These are pretty hearty engines. I don't think you're going to have to bore it to get it well enough to run the rest of the season.

But since the boat is gonna get resto'd too, you might as well work that motor over completely while you're waiting for paint to dry. In that case, 1200.00 is minimal. If you're like I think, you're gonna give it a little special treatment and it'll be more like 2000.00 maybe 2500.00.

You're probably thinkin now that you could buy a rebuilt power head for that. Well that's right and wrong. Yes you can buy one but no it won't be as good as you could do yourself for the same price.

FYI watch out, its addicting, I'm on my third and have a fourth in the wings.

 

[mogfisher]

Re: Should I run it?

I know what you mean about buying one and doing it myself. I'd much rather do it.

What would a $2k rebuild consist of? I've been cruising the Iboats parts section and looking at the prices of pistons, bearings etc I'm guessing that the 2k price includes all new pistons and bearings.

More power would not be part of the requirements for a rebuild as most of the lakes I fish have a 45 or 55 mph speed limit which my boat should have no problem with. It's an 18' bass tracker with this xr4. I would just want to build it reliably so I wont have to worry about it again for a long time.

I'm probably going to leave the motor on the back burner for a bit since it wont matter if it's fixed if the boat wont float. I just separated the cap and now I have to get the cap to my house. I've got plenty of work to do. Once I see a light at the end of the tunnel for the boat, then I'll pull the powerhead. This will determine if I do an "economy" or a full rebuild. If there isn't enough season left I'll just rip it down completely and do it up.

Thanks again for all your input folks.

 

[j_martin]

Re: Should I run it?

I know what you mean about buying one and doing it myself. I'd much rather do it.

What would a $2k rebuild consist of? I've been cruising the Iboats parts section and looking at the prices of pistons, bearings etc I'm guessing that the 2k price includes all new pistons and bearings.

More power would not be part of the requirements for a rebuild as most of the lakes I fish have a 45 or 55 mph speed limit which my boat should have no problem with. It's an 18' bass tracker with this xr4. I would just want to build it reliably so I wont have to worry about it again for a long time.

I'm probably going to leave the motor on the back burner for a bit since it wont matter if it's fixed if the boat wont float. I just separated the cap and now I have to get the cap to my house. I've got plenty of work to do. Once I see a light at the end of the tunnel for the boat, then I'll pull the powerhead. This will determine if I do an "economy" or a full rebuild. If there isn't enough season left I'll just rip it down completely and do it up.

Thanks again for all your input folks.

I got a rig just like that. Watch out for the transom, the way they installed the aluminum top guard on it over bath tub caulk, the transom almost certainly has to rot. I did my transom and battery deck 2 years ago, and now I noticed the rest of the floor is getting a little soft. When I did the transom I tied the cap in tight at the back, so now I'll have to butcher it up pretty good to get the cap off. I'm hanging loose for now and maybe I will find a later, less fibrous hull to hang this great engine on.

I like this hull except..... It's laid up a bit loose so gel coat nicks will get the foam wet. The wood is not sealed underneath, so the wet foam gets to it. Transom, main deck, and front casting deck are all wood. The v-pad suques, and if I flip it over and gel coat it, I'll be sure to square that off into a real pad.

Here's the transom project.
http://forums.screamandfly.com/forums/showthread.php?t=159482&highlight=transom

 

[mogfisher]

Re: Should I run it?

I got a rig just like that. Watch out for the transom, the way they installed the aluminum top guard on it over bath tub caulk, the transom almost certainly has to rot. I did my transom and battery deck 2 years ago, and now I noticed the rest of the floor is getting a little soft. When I did the transom I tied the cap in tight at the back, so now I'll have to butcher it up pretty good to get the cap off. I'm hanging loose for now and maybe I will find a later, less fibrous hull to hang this great engine on.

I like this hull except..... It's laid up a bit loose so gel coat nicks will get the foam wet. The wood is not sealed underneath, so the wet foam gets to it. Transom, main deck, and front casting deck are all wood. The v-pad suques, and if I flip it over and gel coat it, I'll be sure to square that off into a real pad.

Here's the transom project.
http://forums.screamandfly.com/forums/showthread.php?t=159482&highlight=transom

Nice looking project. Looks a lot like my boat and is built in much the same way. I took it a bit further and the cap is completely separated in 1 piece. The way it got by the splashwell/transom fiasco was to run a sawzall at an angle from outside the boat down towards the floor between the cap and hull. Hard to explain but this ended up cutting probably 6" of the glass off and leaving it attached to the cap. I'm doing a complete job of replacing ALL the foam, including that which is in the stringers and ALL the wood. I'm doing both the casting deck floor and the main floor too. Here is a link to my start.

http://www.bbcboards.net/zerothread?id=527688

Here is a link to another guy doing a lot of work to a boat like ours too. He's been real helpful to me.

http://www.bbcboards.net/zerothread?id=408645

 

[sschefer]

Re: Should I run it?

Nice looking project. Looks a lot like my boat and is built in much the same way. I took it a bit further and the cap is completely separated in 1 piece. The way it got by the splashwell/transom fiasco was to run a sawzall at an angle from outside the boat down towards the floor between the cap and hull. Hard to explain but this ended up cutting probably 6" of the glass off and leaving it attached to the cap. I'm doing a complete job of replacing ALL the foam, including that which is in the stringers and ALL the wood. I'm doing both the casting deck floor and the main floor too. Here is a link to my start.

http://www.bbcboards.net/zerothread?id=527688

Here is a link to another guy doing a lot of work to a boat like ours too. He's been real helpful to me.


http://www.bbcboards.net/zerothread?id=408645

Depending on age, that foam is probably the old style. The new pour in is non absorbing but you might try what I did and that was to use pool noodles. I stuffed my bilges, (except down the center) and got plenty of floatation in. With all the weight I carry I think the only way it will level float is resting on the bottom but what the heck...

 

[j_martin]

Re: Should I run it?

If I go to the trouble to rebuild my boat, I'm going to install custom rubber bladders.

The foam they use will absorb very little water, but it will absorb water. The trouble with this boat is the layup is pretty dry, and if the gell coat gets nicked, it leaks. Anything I had open got a coat of cpes epoxy sealer, and the worst looking parts got a coat of thinned fast cure epoxy on the inside.

Again, If I go to the trouble to fix it, I will sand the inside smooth and epoxy a layer of 6 oz weave in for waterproofing.