‘89 150 v6 rebuild kit

[Zep25]

Looking at a rebuild on my 150 v6 cross flow. Any thoughts on good rebuild kits? Pitfalls at this part of the process?
Thanks.

 

[racerone]

Do you have the motor apart now , yes or no ?------Do you know if pistons are original now or already O/S from previous work , Yes or no?

 

[Zep25]

Don’t have the motor apart. Just pulled the heads and I have multiple scored pistons.
I dont think the engine was ever overhauled previously. Is there an easy way to check that? Looks like they have the orig part numbers imprinted on the piston heads...393924.
Thanks

 

[flyingscott]

WSM makes.a.good kit has everything you need.

 

[Scott Danforth]

you measure the bores, assess the damage

you then machine and hone the bores to the size they clean up at

then you buy pistons and rings

 

[Zep25]

I’ve heard this engine is a “low compression” engine. After acomplete rebuild, what kind of compression numbers would be appropriate?
I’ve read these engines were close to 90 psi brand new. ?
I dont think I’m comfortable rebuilding an engine and only getting 90 psi out of it.
Thoughts?
89 Johnson J150stlcem

 

[flyingscott]

How.is that a low compression engine? Dont mistake the engineered comopression ratio as low. Your engine ran almost 30 yrs with 90 psi and you were none the wiser. Rebuild it and go boating. The V6 looper motors from Omc only ran about 90-100 psi.

 

[Zep25]

I thought the 90 crossflows were also low compression engines. That’s good. So, with a complete rebuild, I can expect at least 115psi after the break in?

 

[flyingscott]

No you will not see higher compression. You cannot just wish for higher compression and expect to get it. I used the looper motor as a comparison to your.crossflow to show you thje compression ratios are similiar. There is no magic fix to all.of a sudden get more compression than the factory designed into it.

 

[Zep25]

I see. So both these engines are considered low compression, and were running at 90-100psi off the assembly line. Just wanted to get a good idea of what we could expect following the rebuild. Thank you.

 

[Rustywrench]

I may be going against the grain here a little, but I see no need to buy a rebuild kit for this model motor. You do need to take the powerhead apart first to assess what size pistons you are going to need. Your machine shop needs to measure the bores to check for wear. Some may be able to stay standard, but replace ALL the pistons! Of course you need to bore the scored cylinders. Nothing wrong with only boring the effected cylinders. This is not a car motor. Pistons, rings, & gaskets/seals will usually take care of your problems. The rebuild kit idea is working on the assumption (like cars) that you need bearings. No wear associated with roller bearings as long as lubrication has been adequate. You will be able to tell if that is a problem & the components (crank, rods, etc.) will be shot if there is a problem. Just bearings aren't going to help. JMHO! I have only been doing this for 57 yrs. Also a factory rep. I would hate to see you put extra money in a motor of this age/design. Good motor, but you will not get your investment back unless you keep it & use it up!

 

[Zep25]

Pulling the powerhead and disassembling everything this weekend. Hope to find my crankshaft still in good shape. Anything specific I should look for when examining the crank, rods, end bearings?
I know I have at least 3 scored cylinders, and 2 more that are suspect. I was planning on boring all 6 cylinders, but I’ll wait and see what the shop says and how bad they are. You think it’s more economical to buy the individual piston/rings, gasket kit instead of the whole “kit”?
We only use the boat about 5 weeks out of the year, so we hope this overhaul gets us another strong 15 years of worry free fishing.

 

[Rustywrench]

Ask us again when you get it torn down. The bottom crank bearing locates the crank. It runs in all the trash so it would be the one exception if everything else looks good? You will see WSM Pistons in kits & available separately. I have had good luck with them. You will need a complete gasket set. Plan to do thermostat kits. Some rebuild kits don't even include those? In your model motor the pistons are all alike, just face port & starboard for each side (no ports in the pistons). It is your decision which way you go, but with the average kit running over a thousand dollars you can buy a lot of parts for that.

 

[Zep25]

Got it torn down. Don’t have the pistons removed yet (waiting on the 5/16” thin socket). Crank looks pretty good (never seen a crankshaft before). No obvious cracks. Bottom bearing has a little bit of speckled rust, but still turns pretty smooth. I do see one small wear spot on the top race, but it’s smooth. I’ll probably replace it anyway. Middle bearings have some discoloration, but are smooth and turn well.
A few of my piston rings were stuck (inspecting through exhaust ports), probably how the cylinders were scored.
Rod ends look good and all are still aligned well.
Anything I should look at specifically or more closely at this point?

 

[Zep25]

[No message]

 

[Zep25]

Ok. Finally pulled the pistons. All are in pretty bad shape. No doubt, I’ll replace them all.
Wrist pins are a real bear to pull out. Gunna try some
heat today and see if that helps.
Do all those little needle bearings go bad, or can I reuse them with the new pistons?

Also looking to replace all my fuel lines. Any specific type of line, or good place to buy?
Thanks as always.

 

[Bassmassterbill]

What made you decide to start tearing into it?

 

[racerone]

He is taking it apart because it needs overhaul !!

 

[Bassmassterbill]

But why was it low on compression or not running good how did you know it needed the rebuild?

 

[Zep25]

It was idling rough and pouring gas out of the main prop exhaust into the water. I know those engines like to drink, but we were getting less than 1/2 mpg. I think at least 50% of the fuel wasnt being ignited in the pistons. Compression on all cylinders was around 60psi. Pulled the heads, 5 of the 6 cylinders were scored pretty bad. Total overhaul time

Everything is now apart. Sending to the machine shop this week (hopefully). $365 for all 6 re-bore and hone and “hot dip for the block”.

Looked like the crank, rods and bearings were in good condition? Check pics and let me know what you guys think.

Are the middle bearings on the crank replaceable?

Also looking to replace all the under cowl fuel lines. Any reputable online shops you trust?