Considering purchase of 1990 Johnson GT150

[fd20b]

This motor is on a 1990 Javelin 378F/S. The engine (no hours meter) appears to have been used little.<br /><br />Any particular trouble spots with this motor? What should the cylinder compression read? What should I replace before launching next season?<br />All suggestion's appreciated.

 

[hondon]

Re: Considering purchase of 1990 Johnson GT150

Just considering? I would hope that you have taken this thing on a nice long criuse comparable to the type of use you expect to give this machine.Get a feeling for what things have been done to engine in the form of regular maintenance and when things like the waterpump and gear oil were last checked or better yet changed.This engine is the typical OMC V6 format of the time and a tried and true performer.VRO oiling is not my favorite oil injection system but there are alot of those systems out there and still pumping away on units older than this one.

 

[fd20b]

Re: Considering purchase of 1990 Johnson GT150

Thanks for the insight, hondon. I'm looking to capitalize on off season pricing, but since it's a little chilly in upstate NY, a long ride is not an option.<br /><br />Maybe good compression, clear gear oil, and pumping water are good indicators?

 

[Solittle]

Re: Considering purchase of 1990 Johnson GT150

Yep with compression >100 lbs and all cyl within 10 percent of each other.

 

[Till]

Re: Considering purchase of 1990 Johnson GT150

Sounds like a good one. Get rid of the injection and go 50:1

 

[fd20b]

Re: Considering purchase of 1990 Johnson GT150

Till, I get the message behind your suggestion, however I really don't want the hassle with pre-mix.<br /><br />I've heard that the VRO's are expensive to replace. Are they rebuildable?

 

[DJ]

Re: Considering purchase of 1990 Johnson GT150

fd20b,<br /><br />Since you're not really sure about the history of the engine. Here is what I would do with the VRO.<br /><br />1. Empty out the old oil in the tank.<br /><br />2. Replace the pick up screen (sock).<br /><br />3. Inspect all oil lines.<br /><br />4. Replenish oil and mark a line on the tank (oil).<br /><br />5. Pre-mix 50:1 until you verify oil useage.<br /><br />6. Make sure the warning circuits are working.<br /><br />Actual failures of these systems are really pretty rare. Lack of maintenance gets most of them.<br /><br />You should be good to go.

 

[fd20b]

Re: Considering purchase of 1990 Johnson GT150

Compression reads a steady 95 lbs. on the left side of the "V" and 100 lbs. on the right. I used a $20 compression gauge. I'm told gauges can make the difference in readings??? Plugs had, in my opinion, normal build-up.<br /><br />Started motor (very cold outside). Smoked less after warmed up. After motor was warm, water flowed out of exhuast ports on shaft (thermostats open?). P- stream a bit unsteady. Motor is on it's original water pump.<br /><br />Visually the powerhead looked new. <br /><br />This boat and motor is from the original owner. He has all documentation.<br /><br />Comments?

 

[Dhadley]

Re: Considering purchase of 1990 Johnson GT150

If its easy, look at the part numbers on the heads. They are cast in and will be 6 digits. Let us know what they are.<br /><br />Good luck!

 

[fd20b]

Re: Considering purchase of 1990 Johnson GT150

Unfortunately I'm not close to the boat. However, I have the following details off the motor:<br />MOD: J150STLESB ID#: R08282270

 

[Solittle]

Re: Considering purchase of 1990 Johnson GT150

With a 12 year old water pump I wouldn't run it at all until the pump is replaced for fear that the impeller would disintegrate and send bits and pieces everywhere to clog-up the water passages.<br /><br />After the water pump I would check the documentation and find out when the plugs were last changed - also lower unit oil. Change the water seperators (or install them if not there) and make sure gas tank, lines, etc. have fresh fuel.<br /><br />Last - get a manual for your motor if you don't have one already - and read it.