Johnson 200hp - Over Heating

[majed1965]

Hi All,

Just bought a huge Swift Craft 6.2m cruiser cabinet yesterday with a 200HP Johnson outboard. The boat & outboard are around the early to mid 80's. Hull and trailer in excellent condtion. On land the engine started ok and sounded good. Noticed though that not enough water was pumping out. The boat hasn't been used for about 7 months.

Anyway, took the boat out for a run today. After a few hundred metres the engine overheat alarm sounded.

Turned back to the ramp. The outboard was hot, but seemed still ok. Took it out of the water and put on some muffs. Took off the Thermo housing and found no thermo installed. Started the outboard and found only a trickle of water going through the powerheads with some salt residue visible. Checked the plugs which were old but seemed ok. For such a big engine, it was no wonder it heated up quickly. I rang the guy i bought it from and he said he was not aware of any issues with the outboard. (typical answer i suppose)

Before i go and spend big dollars fixing it, can i trouble shoot it further myself without much work?

My question before is, could it be a blockage? If so, can this blockage be fixed without pulling half the engine out. Can i somehow try and backwash or do something to clear out any blockages?

Could it be a water pump issue o r impeller ? If so, are they easily removed.

Or is it something much more serious?

Any advice is greatly appreciated. Regards, Majed.

Edited January 13, 2009 by Majed

[WANNAFISH]

For piece of mind I personally will take it to Huey and get a full service as it wouldnt hurt to get that water pump replaced and other bits that goes with the service. Theres nothing worst than breaking down in the middle of nowhere and at the same time blowing up your engine and spend thousands of dollars which you could have avoided it first place.

Huey will look after you as he does to all fishraider members and most importantly hes a Johnson/Evinrude specialist.

[pelican]

Hi Mate

It may be as simple as a impeller and I hope it is but when it is a new ( to you) boat you really need someone who you can trust to access the true condition of the motor and if Ok do a service and a tune and then you will have the best opportunity to have a trouble free season out of her. You'll probably get advice on having the motor and trailer set up properly at the same time as so many never are.

There are many possible reasons for overheating and not all are cooling related

If you aren't mechanically inclined it is easy to get stuck with a big bill and lots of half jobs done on boat motors and no preventative jobs done which leads to very unreliable and frustrating boating let alone the danger you place yourself and family at.

Impeller change on the surface is simple and a half hour job and not expensive on parts but there is lots of other things to check at the lower unit at the same time. Be it the annodes, gearcase seals , gearcase oil etc. As with all older motors with unknown service history a 30 minute job can get a lot longer with previously butchered bolts or even stuck or cross threaded bolts.

Once all that is done then as small issues arise you can choose to spend the time and solve them yourself as you learn more about your motor.

Bite the bullet and get it done or at least accessed up front and save yourself the hassle in the long run. Book it in is my thoughts

Edited January 13, 2009 by pelican

[a boat]

Hi, as the guys have said it could be alot of things. Considering you are new to owning this rig and I guess you do not have a service history, I would do a water pump service and replace the water pump with a new water pump kit. With the gearbox off you can see if the water tube is blocked and really considering its age if the cylinder head gaskets are original they need to be replaced as preventative maitance and in doing that you can clean the water passages and replace the deflectors that swell with salt and age and can block the water flow around the powerhead causing an overheat situation. Also your engine should have thermostats installed.

As Pel said with old engines things can add up pretty quickly but to do it right you should do all of the above to giev the engine the best of surviving and not overheating.

Cheers,

Huey.

[majed1965]

Thank you all for your advice and recommendations.

One other question, Why does this outboard not have a water output hose under the cowling. My old 1977 70HP Evinrude has a hose that comes out from under the cowling to disperse water out. This Johnson 200HP doesn't seem to have one. I have looked and looked and cannot find one. So where does all the water desperse from. Regards, Majed.

[a boat]

Hi Majed, what is the model number of the outboard becasue you might find she is older than you think if it does not have a tell tale.

No big deal if it does not because the tell tale is just there as its name suggests and most water exits the powerhead thru the exhaust housing and thru the prop.

Post the model number.

Cheers,

Huey.

[Bojan]

I've got twin 90's from the 80's VRO models.

Had the same problem with the alarm going off. I check the lot for overheating problems.

Checked the rubber dividers inside the heads the impeler and all.

Shortly after I rebuilt both motors and on the first run the alarm went off again.

I got a temperature stick and stuck it onto the engine to find the temp fine (stick not melting)

I since changed the thermocouple for the alarm and had no issues since.

In your case however, I would do a service definatelly and get those thermostats put back too. Running an engine cold is nearly just as bad as running it hot.

Impelers are always a problem because some people decide to run the boat without water. Most impelers are rubber and get stuck to the pump housing when they dry out. Without water they rip up to buggery.

Water acts as a lubricant for the pump.

I always turn the engine by hand to free up the pump before starting if the enigine has been sitting for a while.

My temperature gauges on the old controls are not accurate either I ended up putting temp sensors in the water hose so I can see what is going on. It is always good to be able to see this while running the engine.

Edited January 16, 2009 by Bojan

[majed1965]

Hi Majed, what is the model number of the outboard becasue you might find she is older than you think if it does not have a tell tale.

No big deal if it does not because the tell tale is just there as its name suggests and most water exits the powerhead thru the exhaust housing and thru the prop.

Post the model number.

Cheers,

Huey.

I could only find the serial number of the outboard. The model number is badly worn out and not visible. So i am not sure how to determine exact year it is.

[a boat]

I could only find the serial number of the outboard. The model number is badly worn out and not visible. So i am not sure how to determine exact year it is.

Hi, that makes it hard, but one day swing by and if I look at the engine I can tell you the year model. As mentioned I would do the service on the water pump, cylinder heads and thermostats if all original and that should solve your overheating problems.

Cheers,

Huey.

[majed1965]

Hi All,

Finally managed to fix the overheating issues with the outboard.

A service was done on the water pump, new impeller, cylinder heads were removed anf=d cleaned, new head gaskets, plugs. Motor runs fine now. Mechanic said it is going good. Thamks to all for their help

We took the boat out for a run but it would not go onto the plane. There is no RPM gauge to determine how its going. The mechanic jumped in and said the engine is running A1 and the carbies were good. He said the issue is with th propellor. It has a 21 pitch propeller which is too high. He recommended before we buy one to test out some smallet pitches starting with 17 and then 15 and see how it goes. This will be done on Thursday. It would not get up on the plane at all with the 21 pitch.

Does the propellor pitch make that much difference in power?

Edited January 20, 2009 by Majed

[pelican]

Yes it can, but if the bloke you bought it off had used that propeller before and at least had the boat planing something is up.

Unless your mechanic had a test wheel on the motor in a tank or a test tank where he could see it running under load I would not be buying new props and would be looking at the fuel, carbies and ignition advance or even a dud plug or coil.

Did your mechanic compression test the motor so you know it's general condition of wear? How smooth is the old girl at idle and should have a really crisp even crackle just above idle on muffs?

When you are 100% motor is running as it should , set at correct height and trim I would look at props and ensure that you are getting WOT revs.

Overloaded or with carbies or timing out of adjustment will mean a quick death for a old 2 stroke.

[a boat]

Hi Mate, a 200HP on your old girl will plane if running right with a 21 inch prop, yes it will not see it ideal WOT RPM of 5500 and I would be saying it will perform better with a 17 inch, but the fact that it did not plane at all is due to another problem I would be guessing. Good idea to try before you buy with a 17 inch and see what happens and with normal load you want to see about 5500 as mentioned and yes having the correct prop is the most important thing for engine that is running as designed in relation to performance, fuel economy and engine life. I think it would be wise to get the Tacho fixed or fit one to determine you have the correct prop.

Cheers,

Huey.

[majed1965]

Thanks for your tips.

We will only be trying used propellors tomorrow. We will try different pitches until we find the most suitable one before we purchase a new one. Hopefully this will fix the problem as the mechanic said there is now absolutely nothing wrong with the old outboard.

Below is an extract i found in an old OMC manual:

"The propeller is the final link between the boat's drive system and water. A perfectly maintained engine and hull are useless if the propeller is the wrong type or has been allowed to deterioate"

Lets hope it is the propeller so i can hopefully be at rest.

[majed1965]

Here are some pics of the boat....

[majed1965]

Marine mechanic checked compression which was 115 psi for all six cylinders. He said it was good for an old engine. Will test out with a couple of propellers tomorrow and see how it goes.

[majed1965]

Problem with boat has been fixed...

New water pump, impeller, head gaskets, hoses, plugs, leads and 1 coil.

Propeller was also changed to a pitch 15. A temporary tacho was connected by the meachanic for testing until i get one permanantly in. Boat flew onto the plane and was running full bore at 5500 RPM's. This looks like the correct pitch for this boat. This motor has a lot of grunt in it.

Just finished cleaning it up today and getting it ready for the weekend.

I am really happy now. Thanks to everyone for your help.

[pelican]

Glad to hear

Especially glad to hear there was a coil that needed replacing as it goes to partially explain lack of power. Timing, advance and carby mix ore the others taht could be out if it isn't pulling like a drag boat with a 15 on it.

Depends on what brands of props you are using but that motor I thought would pull a 3 blade 17 inch pitch prop unless that hull is even heavier than standard ones. What diameter and how many blades or brand is the prop you tried?

Pel