Lower unit service. Advice needed please.

I am going to service the lower unit on my 1980 Johnson 55. (55EL80C) <br />There doesn't appear to be anything wrong down there, but the engine is new to me, and I don't know when it was last done.<br /><br />Where I live, I can't buy Johnson spares off the shelf. They have to be ordered, and take several weeks to arrive. Therefore, I need to know what parts I need to order, so that I don't get stuck half way through the job and have to wait more weeks for any additional parts to arrive.<br /><br />Having looked at my manual, I was going to order a water pump kit. Does this come with drive shaft grommet and water tube grommet?, or do they have to be ordered seperately?<br /><br />Also, do I need an Inner exhaust housing seal and a gearcase to exhaust housing seal? <br /><br />Are there any other parts that I need? And is there anything else I should be doing while I've got the lower unit off?<br /><br />Thanks in advance<br />Steve

Re: Lower unit service. Advice needed please.

If you are going to reseal the gearcase, you will need 2 upper drive shaft seals, 2 prop shaft seals, upper bearing carrier O-ring, lower bearing carrier O-ring, shift rod O-ring, and shift rod housing gasket. You may, or maynot have to replace gearcase to exhaust housing gasket. All else is in water pump kit.

Re: Lower unit service. Advice needed please.

Hi Stevie<br /> Water pump Kit OMC part#391635 Should have everything you need. This kit comes with a new housing.<br /> Part# 390770 is a kit with out a new housing.<br /> Part# 389589 is for the empeller only.<br />The first option has it all. Of course it costs the most also.<br /> I would not suggest ordering the other parts you mention, unless you find them in unuseable condition. Toss in some gear oil and a pair of new gear oil plug washers and your done.

Re: Lower unit service. Advice needed please.

Thanks R.Johnson.<br />I wasn't actually thinking of re-sealing the gear case, although I will if it is recommended.<br /><br />I was just going to overhaul the water pump, change the gearcase oil and give it a general clean up. If the old gear oil looks O.K, is there any need to re-seal the gear case?<br /><br />O.K, just read Alcan's post. I'll get the kit that comes with the housing, and hopefully that'll do me.<br /><br />Is the inner exhaust housing seal included in the water pump kit?<br /><br />Thanks again for the good advice.<br />Steve

Re: Lower unit service. Advice needed please.

Hi stevie<br />No, the inner exhaust seal is a separate item. They do go bad from time to time. Mostly from burning do to excesivly hot exhaust gasses, which is usually caused by a defective water pump (a general over heat situation). No need to replace this item during routine preventive maintance, unless damaged beyond use. These seal are a heavy rubber (neoprime) gasket. They are used to stop exhaust gasses from bubbling back up the exhaust housing and getting trapped under the engine bonnnet. This condition causes the engine to choke on it's own exhaust. No fresh air no run. One other thing to do is test the t-stat. No need to replace that either if it passes the test. Mainly to check for stopage do to corrosion or derbis.

Re: Lower unit service. Advice needed please.

Hi Stevie<br />Just another thought. If you get the kit with the new housing and find when you disassemble the L/u that the old housing is still in good shape. Save it for a spare. The when you do your annual P.M. and inspection all you will need is an empeller. Be sure you reassemble all the nuts and screws with some type of anti corrosion greese. Also the splines on the drive shaft. Good luck.

Re: Lower unit service. Advice needed please.

Hello<br /> dude take it from someone who does mobile marine repairs for a living. buy the complete kit with housing. buy some spare oring or the correct gaskets for your drain and vent plugs, buy the exhaust seal cause they are cheap compared to being down several weeks.<br />the drain plugs on the ole jonnyrudes are different. there were 3 types made that will all interchange with the correct gaskets and leak like a sieve without the correct gaskets.<br /> type one, the face(gasket surface) of the plug is smooth. this requires a paper type gasket like merc uses. type two the face has a set of small raised circles on it. this one takes a plastic washer. type 3 the face has a groove cut in it for an oring. the washer and the oring were the most common but until you physically look at yours who can say? order all and use what you need. if it takes that long to get parts then find out which ones you have and order them all. I would also recommend a pressure valve grommet and t-stat and seal replacement. order the grommet,t-stat and seal and the water cover gasket. well enough rambling for now<br /> good luck and keep posting

Re: Lower unit service. Advice needed please.

Thank you for the excellent advice.<br /><br />I'll make a list and order the parts soon.<br /><br />No doubt I'll be posting something on here when I get the parts and start the jobs. Nothing is ever straightforward ;o)<br /><br />Thanks again guys<br />Steve