Alternative to The diverter tubes in the head? 1977 Johnson 140.

[AntiqueTbird]

Hello Fellow Boaters,

I want to share a tale of exuberance and sorrow. I have a 1979 Thunderbird Formula 18 O/B with the original 1977 Johnson 140 Seahorse. The engine turned over well and ran when I bought it And I got it for a very good ($0) price. I knew it would need a deck replacement and a transom and being that I've always wanted to do that sort of a thing , I did. New stringers, knife running from the bow eye to the transom and full beam transom capturing the Tow eyes with SeaCast pourable Composite. I then laid in a new poly gas tank and complete deck made of expanded pvc sheeting (1/2") and poured in the space between deck and hull with 4LB floatation foam. Lots of days weeks and months of work cursing, blood and sweat and the motor was ready to be put back on. The motor had been serviced heavily by a very trusted shop. It turned out that it had been severely overheated. So it received all new bearings, connecting rods, pistons, two resleaved cylinders, a fabricated exhaust horn since they are not available anywhere, and many many new parts. Put it back on the old girl and she was great for two years. This past week I took her out of storage and did the things that I believe are normal maintenance things. New fuel filter, new fuel pump(cant find rebuild kits anymore), new water pump kit, new spark plugs, and carbs cleaned. even got her a new shiny S.S. prop. New fuel mixed 50:1 with XD30 and Rec90 Took her out motored around slow. she fired right up with the warm up lever and a little choke. checked fuel flow in the filter Looked great. Checked blubber holes Moving water well. She was warmed up and I was ready to let her horses run wild as I made it to the part of the intracoastal where running is allowed. Hammer drops, She grunts to life and is on a plane in a heartbeat. Seconds later, UH OH. The sound of the overheat alarm. Before I could even respond the boat slowed dramatically, laid down in the water knocked loudly then silence. I kedged my way back to the ramp so as not to risk further damage as I was unsure what caused the sudden, unexpected, hot seize.

It turns out that My now 5 year old Diverter tubes are a swollen mass blocking off the proper flow of water on the starboard side of the head. Magically my compression is still good in order 120, 124, 122, 119 . even more surprising is the fact that the piston that is damaged (needs to be replaced) has the third best number. I am doing the work myself this time. Not because I don't trust the shop I took it to before but time(very critical), and money. Besides I now have a suitable place to tear a motor down and rework it. I have the proper tools and know how. Before I lacked an appropriate place to do this sort of thing.

So the overall problem seems to be these diverter tubes. Is there and alternative? Is there something better?

 

[V153]

No.

 

[AntiqueTbird]

Well thats sucko. Guess I'll add that to my annual inspection checklist Don't want another season opener like this one.

 

[racerone]

You can use solid rubber o-ring material.----I like using 3/8" re-enforced fuel line too.

 

[interalian]

I'd use the OE parts, but seeing how they can crush, I'd stuff the holes with a plastic rod. Noticed other OBs use that method.

 

[AntiqueTbird]

interesting thought on the plastic rods. But I had an even better one (I think). Being that these tubes look and feel like rubber vacuum line and rubber tends to age and swell and crack over time, How about rods of the appropriate size and shape made of a high temp silicon. Something like what they make those oven mitts/Grilling gloves out of. We use it to make seals better on components we put back together. Like gaskets and whatnot. The idea would be to make a simple extruder mold and pump some of that high temp stuff through it and then cut to size. I have personally observed that that material is very high temperature resilient and should hold up to the max 170f that the engine should get to. Any thoughts?.

 

[Joe Reeves]

***************************************************************************

 

[interalian]

I can't help thinking that if this bit of hose had a plastic rod filling the hole it wouldn't have dislodged. That said, when I rebuilt my motor last year I just used OE tubes. As noted by Joe, they protruded about 1/8" but I left them that length so they'd get a slight compression when the head went on.

 

[Joe Reeves]

***************************************************************************

 

[interalian]

That deflector pictured does not look like the proper diameter hose to begin with. Normally a deflector could not move that far over and still appear round..... it would be extremely egg-shaped.

1/8" of that firm hose could result in distortion, but more importantly, I wonder if the excess could be compressed sideways to interfere with the sealing of the head gasket?

The picture is from a '79 140 that I stripped used as a donor block. No idea of their provenance, but I do know it had suffered an amateur rebuild prior to my getting it. Evidence was a misaligned center bearing (photo below).

The new deflectors/diverters/rubber tubes I installed did protrude about 1/8" as noted, but I tested what would happen when compressed, and they just pushed in flush so I just left them. I was tempted to cut them but figured BRP must know how long they should be. My 140 runs like a top now.

 

[AntiqueTbird]

That pic of the "deflector" being mushed past those humps. Mine was swollen and more of a triangular shape that was still in its place but also expanded out to the bolt hole blocking almost 100% of the flow. When I put her up for a few month as of last December She was running great with absolutely 0 issues. I am guessing that sitting for 6 months let the tubes dry out and then when I took her out for the fist run of the season they swelled up. Was perfect until that though.

This is why I'm wondering about an alternative to these rubber sections of hose. Something more stable, less likely to fail.

Apparently the horn failed to sound. I am looking into why that would happen.I did replace the throttle and shift cables so I may have knocked wire loose from the horn and not noticed it.

 

[interalian]

I like the suggestion of a section of the proper OD of neoprene o-ring stock as suggested above as its solid construction should reduce deformation. I did see plastic fillers used on similar deflectors on a Force OB over on another page, so there must be some reason they did it. Some use fuel hose of the proper OD, but unless it's the heavily reinforced stuff used for fuel injection, I would think it's way too soft for this application.

If the horn failed to sound, I'd start by checking whether the horn works at all. Take the rubber sleeve off each of the brown leads from the temperature sensors in the heads, and with the ignition on, ground the connectors. If you get a beep you know the wiring and horn are OK. Testing the sensors isn't possible in place, and replacement involves removing a ton of easily broken 1/4-20 bolts holding the water covers on.

 

[AntiqueTbird]

It's likely bunged up at the controls as I had them apart to replace the cables. As it sits right now, I have the water jackets off and can see the water pathways and tops of pistons. piston #1 looks like it had a 3/8" roundover bit taken to it on the sharp edge of the hump. I'm only waiting on a new piston at this point I have all of the other gaskets and new rings for it. I'll look into the neoprene o-ring stock, but for this season I have the new OEM tubes to put in for this reassembly.

The head is mostly torn down just awaiting the pistons arrival. I feel much better about taking things apart when I have all of the bit and pieces for reassembly handy and ready to go. I don't like the natural spreading that seems to occur when things are left in pieces too long.

 

[interalian]

The head is mostly torn down just awaiting the pistons arrival. I feel much better about taking things apart when I have all of the bit and pieces for reassembly handy and ready to go. I don't like the natural spreading that seems to occur when things are left in pieces too long.

Funny you say this. When I was doing my upbuild (linked in sig), I had the 140 and the 90 torn down at the same time with parts on my work bench, three banquet tables and all over the garage floor. My wife looked at it one day and asked how I would ever put it together. Aside from looking at torque specs, I didn't even reference the SM.

 

[AntiqueTbird]

Got the piston today. Don't bother with them. Looks like new old stock with wristpin, bearings, rod, and rings. It looks like someone played assembled piston bowling with it. All beat to hell. The skirt is oblong from the rod whacking the snot out of it. Its got dents gouges and dings all over it too.

Looks like I'll be going the wiseco piston kit route.

 

[Joe Reeves]

***************************************************************************

 

[AntiqueTbird]

I talked to seller today. He was friendly on the phone and asked that I send him a few pictures of what I received. I did and am waiting for a call back or email on what his solution is. After getting the head off and piston out I'm thinking of dropping it off at a shop and having them do it .030" over and getting a set of wiseco's. They come with the skirt coated for this year and motor and seem to have a pretty good reputation for reliability.

 

[AntiqueTbird]

Ok got the new piston from a local shop. Brand spanking new and Shiny. Power head is mostly bolted back together. Just need to slap it back on the exhaust half.

I'm going with 3/8" Silicone a70 oring cord stock cut to length for the diverter tubes. Seems like a good choice. Its solid, is very chemical resilient, and operates from -30?f - 400?f. It won't break down in salt water and if I use grease or some other petroleum product to slip it into the water jacket it wont hurt it.

I'm getting 10' of that in the mail so if anyone else would like to try it, I'll share.

Seller was very good about the return of both the whole piston and the set of rings. is back to being ok in my book. They pulled all of the rest of those pistons out of stock because they were all in similar condition.

On another note. I'm building a 4 point digital thermometer out of some ktype thermocouples an arduino mega and a 3.5" screen. Something simple that will show the highest temp at all times and flash red and white if it goes above 160?f.

Anyways hoping I'll get a day of scalloping in this weekend. If not Tuesday it is.

 

[interalian]

On another note. I'm building a 4 point digital thermometer out of some ktype thermocouples an arduino mega and a 3.5" screen. Something simple that will show the highest temp at all times and flash red and white if it goes above 160?f.

And I thought I was nuts with dual senders. You'd better share pix of that setup.

 

[AntiqueTbird]

No Title

Ok got her put back together and not one extra nut or bolt.turns out the buzzer is bad. It's a major pain in the hind end to get to and replace so I'm replacing it with a small marine horn on a ground switched relay mounted outside of the control box. If the horn doesn't work then it's the relay or the horn which is easy enough to figure out and will be 100^1000000% easier to replace.

Also here is a pic of the new improved diverters.