Outboard cooling channels blocked ...

[Guest]

Johnson 4 Seahorse twin ....

Took to service people and they didn't want to do it ..... yeh - they turned down work !!

Anyway ... I've heard that fluid can be injected into the water outlet to 'back-clean' the passages ..... the notes I read talked of inverting the engine and injecting in .... leaving it for a while ... then standing on side, then upright ..... letting it drain out the intake .....

Sounds too good to be true and also I am concerned about the leg oil when its inverted ......

C'mon panel - someone must have the answer to my J4 woes !!! If it is possible - what fluid to use and method ....

 

[TigaWave]

I've just got a Johnson 2.5 twin going again which had blocked intakes and was seized...are you sur eits not just a bloackage there?

The leg oil is safe as theres an oil seal below the water pump, which is just above the cavitation plate, inlets have small gratings and are either side of the pump body...so you can check these.

It may be worth just dropping off the bottom of the leg and renew the pump and clean out the inlets.

My concern is that the water outlet is up high near the exhaust and if you turn it upside down water will go in the exhaustt ports? the inlet goes up a pipe from the pump but on mine the outlet exits just below the cylinders.....assuming its similar, but I believe its the same engine almost. I'd check this with a manual or drawing before I tried it.

 

[Superflid]

I had some luck clearing a few years worth of deposits from a very corroded Mariner insides using a bicycle brake cable inner wire, then flushing through with water.
It's still running.....

It looked like this when I started!

 

[Talbot]

dont suppose it is much more work than a 2hp yam. I used to pull that apart every couple of years to make sure the passageways were totally clear. just take off the cowling and fuel tank, then on the yam you only had another 10-12 bolts to undo - the cylinder head, and the join from engine to leg. Biggest problem was always seperating the engine from the shaft, which is probably why the repair people didnt want to know.

 

[BarryH]

I had good results with Cillitbang on a mariner 20. Plugged all the outlets and water inlet pipes, took off the thermostat cover and filled the waterways up with that. Left it for 15 mins emptied it out fitted a new pump impeller and run it up in clean water.

The crud and crap that came out was astonishing. Doesn't run hot anymore and the cooling water telltale jet is very strong. Not bad for half hours work and £2.50 of household cleaner.

 

[VicS]

Nigel,

FWIW twice when I had cooling troubles with my 6hp 'rude I found the problem was not blocked passages, in fact as far as I have been able to see they are remarkably clean, but corrosion around the rubber grommet at the top of the water tube squeezing it closed over the end of the tube.

As I dont know the year of your O/B I can't look into to possibility any further but the engine parts diagrams on the Bombardier-Evinrude website might help you to identify the bit I am talking about. You will need to go to the diagram of the "gear case" to find it.

I agree with others that the oil is no problem when you invert the engine but you are very, very likely to get water, and nasty chemicals, into the exhaust ports.

I hope this may be of some help, its a bit more relevant than experiences with other makes perhaps.

 

[Guest]

Separating engine ...

Yep - thats where he baulked at it ... saying it could lead to damaged bolts etc. and basically run up a bill way outside of expected ...

He also said that often a good blast from an air hose BACK through the system often clears it ... but I don't have a handy compressor !

I have the Johnson repair manual and often drag it out for a gander .... never stripped an o/bd before .....

Interested in the CilitBang and also the blocked inlets .... as outlet steams when run ... so I think blockage is before engine ??

 

[Talbot]

Re: Separating engine ...

If steam can get through, then it is possible that a strong de-scaler (e.g. fernox) could do the trick or even a very concentrated vinegar solution, with the outboard being run in a bucket (without the prop!)

 

[Peppermint]

Re: Before you get all excited

with chemicals and such. Have you tried blowing an airline up the outlet?

Worked a couple of times with my Tohatsu's.

 

[Guest]

Very wary of running it without cooling ...

I have a large 40 gal drum specially mod'd to take an o/bd ... but I am afraid to damage the water pump / engine etc, with overheating ...

I will have to think about this carefully ... as its a good engine - despite my no liking Johnson normally !!

 

[Talbot]

Re: Very wary of running it without cooling ...

run it in the tank for a short time until steam starts or it starts to feel hot, and stop, let it cool down, repeat until clear, as the descaler will slowly work its way around doing its job. if it doesnt, then you will have to try to get it apart. if it hasnt been apart for some years, this may be impossible depending on whether it was greased up properly when previously asembled.

 

[andy_wilson]

What a great engine, mine is 15 years old and has had minimum maintenance and performed without fault until....

This year, the second run of the season, after about a month of non-use, the engine was seized.

I thought it was the power head but it has been seized every time this year. The fly wheel has slight movement and pistons are moving slightly. Judiciously back and forwarding gets it moving stiffly until I can start it (still a bit tight).

Once running it is perfect, as powerful as ever, works OK all week, but seized solid after say a fortnights rest.

Suspect the problem is in the leg or posibly bottom crank bearing, but would be interested in any ideas / comments.

N.B. I am told these engines are not exactly prone to furring up, having generous cooling channels. Putting any water / acid in upside down is not a good idea, run it upright and let the pump do the work.

What exactly did they turn down doing?

 

[Guest]

Turned down stripping ...

They reckoned that the age and apparent condition when they lifted the cowl off showed that the engine / leg etc. had probably never been separated in all its life ... so they were worried that bolts / bits might shear / break when they tried to split it ... increasing the bill as they worked ...

The guy is a friend of mine and basically he said "Nige ... see if you can blow it all out etc. air hose or whatever --- stripping this engine may not be a good idea etc. etc."
I had also taken my little Mariner 2.5 for same reason and he was happy to do that one ... in fact less than an hour and all clear ...

I will try the bath and de-scaler idea .... but its going to take a lot of stuff - as my bath is a 40 gal drum !!

 

[JIM_TEAL]

I agree with Vic-s. I was given same advice on mine. Strip block off pan carefully and clean out. Best get a gasket set before you start. Clean out all the salty gunk and re-assemble.
Reinvigotrated good engine. Bousn's mate got my gasketset.

 

[William_H]

Hi Nigel I have had a lot of experience with the 6HP. You should be able to remove dismantle pump and gearbox shaft comes out of engine sometimes requiring the engine to be turned. There is a copper pipe on the 6 which takes water from the pump. It should be possible to get good flow through the engine and tell tale by putting a garden hose to the pipe. If not......
The cylinder head is easy to remove but take off the thermostat housing first.
The trick is to be very careful with every bolt, Use a spanner with short handle and if it doen't come free then use heat on the bolt head. They can snap off easily. In which case if it is only one sometimes you can ignotre it and don't dismantle it. Just give it a go. If you can't dismantle then try cleaners. Sorry if 6 is radically different to 4 good luck olewill

 

[Guest]

Olewill .... what engineer said ...

The engineer was reluctant to try when he took cover off and saw what appears to be an engine that has never been taken apart ... he warned that bolts etc. would probably snap and then bill would start mounting up ....

I will check out the manual again ... as I have the Johnson O/Bd manual for servicing / repairs etc. - but when first looked through - it appeared not so simple ...

 

[VicS]

Re: Olewill .... what engineer said ...

Nigel,

Another word of warning based on my experiences with the 6hp. That is a long shaft model and the drive shaft runs in a nylon bearing in the leg extension piece. If the lower unit is removed leaving the extension piece on the leg, corrosion on the shaft prevents it sliding through this bearing so the shaft pulls out of the top of the water pump instead and the impeller drive key damages the top of the pump housing. Not too badly if its a plastic key but the original metal key will wreck it! So the extension piece (and shaft) must be taken off with the gear case.

Hopefully your manual will cover this if applicable but I thought I would warn you in case you are like me and only read the manual after things have gone wrong.