87 Evinrude 90hp. 2 leaks, loss of horsepower

[smokinjoefission]

Hi everyone.<br /><br />First of all, let me say that I think I've found the Nirvana of Outboard forums! This is one awesome board full of great information.<br /><br />Anyway, on to the sad stuff: I've got a 1987 Evinrude V4 90hp pushing a 17.5 foot K&C Thermoglass. I've had the boat for just over 1 year now. It's run pretty good for the last year (although I've only put about 50 hours on it). <br /><br />Last summer, it started to idle rough and lost power intermittantly. I bought the shop manual and tracked down the problem to bad check valves. I replaced those and the problem was solved.<br /><br />I've had the boat out in a total of 4 times this year (all within the past month), and it started to idle rough and lost power again. I did a compression check last year and all cylinders were around 120 psi, with a 10 psi diff between the highest and lowest cylinder, not bad at all.<br /><br />The last 3 times I've had the boat out have been mostly idling (literally) around the bay here (4 nights of fireworks display on the water). The engine's performance got gradually worse again, to the point where I can barely get it up on a plane with just myself in the boat. <br /><br />It doesn't feel like any single cylinder is misfiring or dead, just a rough idle and the motor's not able to get up to full power.<br /><br />I checked the check valves again today as the symptoms were identical, but they turned out to be ok.<br /><br />In the next couple of days, I'm going to run a compression check on the cylinders and confirm that all cylinders are firing.<br /><br />The worst part of it was coming out to the boat this morning and seeing a puddle of chocolate brown oil leaking from the bottom end. No doubt the prop shaft seal has gone, and I'll be replacing that before the boat goes in the water again.<br /><br />My other concern was the trail of brown oil running down the leg, as well as against the motor mount on the transom ( http://www.smokinjoefission.com/images/evinrude_leaks.jpg if you want to have a look yourself).<br /><br />Is this indicative of a blown seal and a possible cause of loss of power? Is it possible that the prop shaft seal and this leak are related?<br /><br />Thanks in advance for any information and I'll post back with my compression and spark results.<br /><br />SJF<br /><br />PS: Check valves ... what the heck are they for? I've spent many hours rebuilding automotive engines from small 4-bangers to monster v-8s, and have even done a few small 2-stroke motorcyle engines, but I've never come across a check valve in this kind of application. The shop manual just makes casual mention of drain plugs, and how to check them, but that's it. Please! Someone explain these to me, it's driving me nuts!

 

[Joe Reeves]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Joe.... The check valves you speak of are fuel recirulating valves, moving excess fuel from one cylinder to another.<br /><br />It sounds like the carburetors have fouled. This happens over a period of time. This condition causes the engine to run lean, and if not corrected will result in piston damage. The cure is to remove, clean, and rebuild the carburetors with complete kits.<br /><br />The above is assuming that the engine has good, even compression and spark that will jump a 7/16" gap on all cylinders with a strong blue lightning like flame (with plugs out).<br /><br />The lower unit leak.... drain the lube, apply 7 to 12 psi pressurized air to either the drain or oil level hole. If a leak exists, you'll be able to see and/or hear it.<br /><br />The upper oil flow draining down the exhaust housing.... remove the two lower cowl pans so that you can inspect that area. That problem should then be obvious.

 

[jbkk]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Joe, <br />I couldn't help but notice that your post sounded hauntingly familiar to some symptoms I have been experiencing with my '93 88hp Johnson, namely rough idle and occasional power loss. You mentioned ending up finding bad check valves and temporarily solving your problem - my question is<br />where are these and how do I clean, check, or replace these? Just wondering, thanks in advance for any help - hope you solve your problem.

 

[smokinjoefission]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

jbkk,<br /><br />the check valves, if your engine has them, are located under your carbs on the intake manifold (if you've got the V-4 like mine).<br /><br />There's 4 of them, one for each cylinder and look like little brass zerk fittings (like you would use to lube your car's suspension with).<br /><br />There'll be a small rubber hose running from each check valve to one of the cylinders.<br /><br />To test them, you'll need a syringe and a length of clear 1/8" ID hose. I went to an aquarium store to get mine. Fill the hose and syringe with rubbing alcohol, and connect the hose to a check valve. If you can push and pull fluid both ways through the valve, then it's no good. You shouldn't be able to push fluid into the check valve if it's ok.<br /><br />You should also check the the other end of the system too: where the hoses from the check valves lead to on the cylinders (I believe they're called the cylinder bypass cover). You should be able to push fluid both ways. If not, then it's blocked and needs to be cleaned out.<br /><br />I was surprised at how much these little brass thingies affected the performance of my engine.

 

[jbkk]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Joe, thanks for the advice - I will try it . Stay in touch and we'll keep these motors running right one way or the other .

 

[smokinjoefission]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Update!<br /><br />I did a compression test today and was pleasantly surprised with the results:<br /><br />#1 - 122 psi<br />#2 - 120 psi<br />#3 - 122 psi<br />#4 - 118 psi<br /><br />I bought a can of Evinrude engine tuner and did the compression test before I used it as a baseline.<br /><br />On another note: Before starting up the engine, I pulled all the plugs, cleaned and gapped them. When I was warming the engine up on the muffs before spraying in the engine tuner, I felt each of the plugs and notice that #4 was warm, but not hot to the touch. I could only hold the other 3 plugs' hex nut for about 4 seconds before they got too hot to bear. I replaced the #4 plug and it came up nice and hot after restarting the engine.<br /><br />I've now sprayed a whole can of engine tuner into the engine while it was idling and will let it sit overnight before running it out tomorrow and doing another compression test. Let me just say what a nasty, smelly, smokey noisy process that engine tuner is! My girlfriend told me that I stink, and I don't think it's my deodorant. I also love the 'neurological and brain damage warning from long-term exposure' warning on the can of the engine tuner. Sheesh.

 

[The Marine Doctor]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Yes...engine tuner can be a party favourite <br /><br />TMD

 

[Hooty]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

After idling for long periods of time, plugs have a tendency to foul. I don't bother cleaning and regapping, I just replace 'um. The fact that after cleaning and regapping, you still had one not hitting kinda reinforces tha need to change 'um.<br /><br />c/6<br /><br />Hooty

 

[OBJ]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Joe....just a question here....has your gas usage increased since the problem started?

 

[smokinjoefission]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Outboard Jim,<br /><br />hell ya! I almost didn't make it back to shore last time I was out. The fuel consumption easily doubled, even at low revs.<br /><br />SJF

 

[OBJ]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Joe...outside chance here you may be getting water into one of the heads either from the exhaust side or a blown head gasket. May be worth a look.

 

[smokinjoefission]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Jim,<br /><br />would the number 4 cylinder being lower in compression than the others, albeit not by much, and the cold running spark plug indicate a blown gasket or water coming in from the exhaust side? Having the exhaust mixed with water is a pain in the butt 'cause if it were a car engine, white smoke in the exhaust would indicate water getting into the combustion chambers.<br /><br />Would pulling the cylinder head show any obvious clues to either problem?<br /><br />Thanks!<br /><br />SJF<br /><br />Oh yeah, one other thing that I noticed when I pulled the plugs that may or may not be related: I noticed that the ground electrode seemed to be worn into a slightly 'U' shape on all the plugs right above the center electrode. I seem to remember reading something (car-related, I do lots of car engine stuff) that might indicate reversed-polarity.

 

[OBJ]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

It could Joe. Or one of the heads could be running cold due to a faulty t-stat. Each one of your heads has it's own t-stat. Have you by chance noticed a difference in the temps of each head?<br /><br />Water induction will usually be represented by a shiney mark on the piston. Water has a way of getting rid of the carbon where it enters.<br /><br />But your compression is still up and that's good. If you decide to pull the heads, start with the side with the lowest compression which sounds like the port side...2 and 4 cylinders.

 

[G DANE]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Hi Smokin Joe Fission<br /><br />The running oil looks like unburned 2stroke oil to mee. It occurs after long time iddling or running cold. The part that exits at lower end is normal. I dont think it is lowerunit oil. Loosen drain plug and look at L/U oil. If not milky, I wouldtn worry. It shouldnt exit at the top end !! Looks like a leaky base gasket. If one of your carbs are flooding a little and you iddle much you will foul plugs and loose performance. Check that all sparks can jump 7/16" gap with strong bluee flame.

 

[OBJ]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Joe....keep us posted as to yer' progress and what you find. Thanks.

 

[smokinjoefission]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

'Nother Update!<br /><br />Whew, I'm breathing a sigh of relief. I went to my local Evinrude dealer and picked up 28 ounces of gear oil, and some new plugs.<br /><br />I decided to drain the gear oil for a further inspection and found it came out light-brown and mostly clear, no evidence of water at all! I guess the oil leaking from behind the prop was just unburnt 2-stroke mix from all the idling I've done recently.<br /><br />I replaced the plugs that were on the motor (some anonymous NGK plugs) with the right ones from the dealer, gapped to 0.040 as per my manual. I love the way they print the word 'Marine' on the spark pug box to justify doubing the price . I fired up the motor (it was tough to start from the engine tuner I'd guess) and let it run for 15 mins to blow out all the engine tuner crap that sat in the motor since last night. I say again that stuff is stinky, nasty and messy, but I'll see if it worked once I get the boat back in the water. <br /><br />I noticed that number 4 sparkplug was still running cool to the touch for the first 5 mins but eventually came up to the same temperature as the other plugs.<br /><br />More to follow if I can get to the water tomorrow.<br /><br />Thanks everyone!

 

[Hooty]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Another water-in-the-cylinder indicator is a real clean sparkplug. Like Outboard Jim pointed out, when ya get water in there, it kinda steam cleans everything.<br /><br />c/6<br /><br />Hooty

 

[hagarwc]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

To save you taking off the heads unnecessarily I suggest you get your hands on a leak tester. It is a great tool if used properly and can pinpoint leaks from all sorts of causes like blown head gaskets, faulty rings etc. in both 2-strokes and 4-stroke motors..... I bought one years ago and is one of the most used tools in my arsenal.

 

[OBJ]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Hagarwc....ya' got my curiosity up on the leak tester. Could ya' post something over in general outboards telling me (us) a little something about it?<br /><br />Thanks.

 

[hagarwc]

Re: 87 Evinrude 90hp. 2 leaks, loss of horsepower

Just a simple device that pressurises each cylinder and measures the % leakage from it. To make your own basic one you need to take an old spark plug, drill the centre out of it and put an air hose fitting on it. You also need an old stethescope and remove the end thingy an work with only the pipe. Can also use a bit of thin pipe to listen for noises. You then screw the modified spark plug into the first cylinder (with all sparkplugs removed)and apply a small amount of regulated pressure (10-20psi). Oh, you MUST put the cylinder under test at TDC and lock it there by one means or another. If you don't the engine will simply spin and put the piston at bottob DC. If you have the gauge connected on the air line you then see the % leakage displayed. (it measures the amount of air passing through it). If you don't have a gauge you will have to use your judgement to decide weather the amount of leakage is acceptable or not. For checking on a possible blown head gasket just push your stethescope pipe into the adjoining cylinder's spark plug hole and listen for compressed air sounds escaping. if the gasket is blown you will hear a banshee noise in your listening device in the adjoining cylinders. Believe me, you WILL hear it! For checking for leaky rings you will have to find a way to get the pipe into the crankcase area and listen for escaping gases there. etc etc for other tests. Just use your imagination for where to listen for the escaping gasses. You will be suprised how accurate it is and with a little practice you will be able to pinpoint where the problem is. I have used for donkeys years now on both 2-stroke and 4-stroke motors (outboards included although they are more tricky to get openings to listen through) and saved myself a huge amount of unnecessary stripping to find the fault. I hope this helps. If you need more just ask but remember my reply will be delayed as I am a long way away....