Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

[murdmerc]

I have a Mercury 40 2-Stroke 4cyl 1991 Classic, only owned the boat/engine for a couple of years and learning slowly.
At the end of last summer while on the water I noticed more exhaust smoke than usual on the boat and after inspecting the outboard found that there appeared to be exhaust smoke and warm water spattering out of the front of the engine just under and around where the steering pivot arm enters the engine. Then paranoid .... I noticed on the rear of the engine opposite this there was oil spatter coming from the 2 exhaust ports leaving spotting in the water - there appeared to be white emulsified oil on the lower edge of these ports also - myabe this part is normal but the exhaust gas and water issue definately seems wrong.

It's been suggested to me that I may have a top and bottom crankcase seal Leaking or blown powerhead and adapter base gaskets. Someone also said that it could be the grommet at the bottom of the exhaust tube ?? Or even a damaged exhaust adapter plate ?????

I hope that there might be folks out there with experience of this or these engines. I would like to tackle the repairs myself but would just like some assurance that I'm going in the right direction before I do so. Also does anyone out there have a nice detailed procedure for this ??

Any help/advice appreciated.

Cheers

Picture below :

See Engine Details : http://flic.kr/p/bvY7Bn

 

[oldman570]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

Your trouble is probly a bad gasket between the powerhead and LU because of the age of the motor. Doing a compresion check and the color of the plugs will tell you alot as to the trouble. As long as we (it) gets older we need things fixed, teeth, eyes, gaskets , and carbs just to name a few. The heat from the exhuast will burn gaskets in time.:redface:
Oldman570

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

I've ordered a compression gauge and will post the results. When I remove the powerhead - will the problem be obvious and what should be replaced?

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

I've taken some photos which show that the rubber "seals" where the steering arm enters the engine on each side - the seals appear to be torn and split. Could this be the cause of the leak or are they just non crucial dirt seals. Maybe the problem is further rooted.

See Photos at :
http://flic.kr/p/bvYjAg
http://flic.kr/p/bvYjA8
http://flic.kr/p/bvYjzX
http://flic.kr/p/bvYjzV

 

[oldman570]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

The gasket that is bad is not in the diagram. Go to" **********" there you will find a diagram for the Driveshaft Exhaust plate listed under 40HP and your SR#. it will be the gasket shown that goes between the plate and powerhead. Get the part number for the gasket and see if you can find it if not on that site. You will need this and others inorder to fix your trouble. From the pictures posted you might consider taking it to a dealer to have it fixed as the corrision is bad on the nuts and studs, and might break off when trying to take apart.Then you will have more trouble fixing them. One would think it a simple, fix but not so without the right tools, a manual, and time.
Just my .02 opinion,
Oldman570

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

See : http://www.flickr.com/photos/76986942@N04/6902690119/in/photostream

Showing Exhaust Plate to Powerhead Gasket and Exhaust Plate to Mid Section Gasket - Do you think it's these two that are the problem ?

27 79650 1 GASKET-POWERHEAD
27 38501 1 GASKET-EXHAUST ADAPTOR PLATE


What about the two rubber seals round the upper mount ? Are these just a symptom of the internal gasket failure ?

Thanks

Well tried to upload the image but as usual doesn't work will try again later

 

[oldman570]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

Those part numbers should be the ones that are bad. The other ruber are the engin mounts to the steering tube and mount and away for the water and exhaust to get out the lower cowling. Take the lower cowling off and you should be able to see everything better inorder to make sure of the leak. Cowling comes off easy. Call Crowley Marine or Iboats befor ordering gaskets to be sure you get the right ones.
Oldman570

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

I'm about to remove ... ahem...... Try to remove ... the powerhead. I've disconnected all the ancilliaries and have cleaned up and being WD-40'ing the hell out of the 8 x nuts for the past 48 hours. Trying desperately to avoid bolt/stud breakage. The only thing is I'm a bit unsure as to what spanner to use - I only have metric and my 10mm is too small and 11mm too loose - I guarantee it is going to round the nuts - So reckon as it's an American motor I will need to buy an imperial spanner but there doesn't seem to be much available between the 10mm and 11mm size. Is 13/32 the correct size ? Anyone know for sure ? - The Nut is officially listed as 11-64809 - NUT (5/16 IN.) at http://www.hbmmercruiserparts.co.uk/...nd=543&bid=140 I guess that 5/16th is referring to the thread size.

See Nuts at : http://flic.kr/p/bvY7Bv
See Engine Details at : http://flic.kr/p/bvY7Bn

Cheers

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

Have a look at this photo - Its not my engine but is the same model - I still have two powerhead nuts which are giving me bother - i'm a bit concerned that there is water and exhasut gas getting into this area - well there must be if its coming out the two forward mounts as in the video.

Appreciate opinions thanks

See Photo of adapter plate at : http://flic.kr/p/bwk97e

 

[oldman570]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

Yes there shuould be some water in side that space at times. It should never get high enought to cause a problem as there is a 1/4" drain hole above the cav. plate on the side of the LU housing that drains the water out. You might want to check out the water pump while you have it tore down,as it might have the ruber slinger missing and or the cup worn enought to let the water pump into that space. Dose theprop have a plastic ring or flared out at the out end of it? If it is not flared and no ring it will cause added back pressure on the exhuast and might cause water to be retained in the housing also. The 5/16 is the stud size and is US thread. The nuts can be heated up with a propane torch some to help with getting them off. Wit bolts you have to heat the housing where they are at inorder to help remove them . Do not heat up the stud or bolt as it will expand and make it worse.
Hope this helps.
Oldman570

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

Thanks for your advice - Well I got the Powerhead off, 3 nuts with my 11mm wremch/spanner - 3 with my damaged nut extractor, and the front 2 with a old wood chisel and a hammer and finally Rubber mallet and it went.

Powerhead gasket looks ok - I damaged it a wee bit while trying to split it with a knife oops - just the gasket damaged though and there is a small crack but otherwise looks ok - the black stuff round the exhaust area is rock hard.
See Powerhead gasket at : http://flic.kr/p/bx5hKV

The adapter plate and its lower gasket seem ok too.
http://flic.kr/p/bx5hKM
http://flic.kr/p/bx5hKR

After removing the shift rod and adapter plate I noticed a washer or at the bottom inside the leg - I tried hooking it but it fell and went out of sight - no idea where it came from but after removing the leg from the 4 x mounts I turned it upside down and hit it a few times with a rubber mallet and still no sign - wierd - any ideas ?
http://flic.kr/p/bx5hL4

Also have attached a picture of the shift shaft is the bend near the bottom normal ?
http://flic.kr/p/bx5jnr

Upper mounts and seals are shot and lower ones may need replaced too - still not sure from all this how water was getting into the upper mount area ?? and escaping through the mounts ? You say there can be water in here from time to time, does it fillvia the cavitation plate ? or do you mean water that shouldn't be there like from the impeller as you suggest?
http://flic.kr/p/bx5hKX
http://flic.kr/p/bx5hL2

Another thing - the manual shows the inlet hose on the oil pump (from the oil resorvoir) to be the top one but on my motor it is definately the bottom one and the top goes to a brass Tee which is linked to the Fuel In connector - is there something connected wrong here ?? Boat has been running fine and using oil as it should ?
http://flic.kr/p/bx5jne



My parts list is looking something like this now :

11-64809 NUT (5/16 IN.) 8x
96401 SEAL at Steering Arm 2x
27-38501 1 GASKET-EXHAUST ADAPTOR PLATE 1x
27-79650 1 GASKET-POWERHEAD 1x
16-68165 STUD-CRANKCASE TO DRIVE SHAFT HOUSING (1-5/8 IN.)
92337 3 MOUNT (Upper) 2x
96401 SEAL (round upper mount) 2x
88238A 2 GROUND WIRE (Port Lower Mount) 1x

75304 LOWER MOUNT **superseded by 2x
753041 Lower MOUNT **superseded by
75304T1 Lower MOUNT

Impeller and ***. Gaskets

I would appreciate yout thoughts - due to the state of the upper mounts and the water leaking through them - do you think they are my main problem or is the water in that leg still needing to be addressed?

Also another quick one - how will I retorqe the p/head bolts as the access is terrible - TQ wrench won't fit

Thanks

 

[oldman570]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

Your on the right track. Time and use has taken it toll on the mounts and need to be replaced. The washer that is in the bottom of the LU looks like it was the slinger ring that should be on the driveshaft on top of the water pump. Most all parts will come in a pump repair kit. Make sure that the rubbers for the water tube are in the water pump and the bottom of the motor, not a bad idea to replace them if they are rock hard or, fit the tube lossely, or split. As for the fuel system, it appears to be correct the way it is , my manual shows it the way it is. Needs the hose replaced from the cowl to the tee check valve ,mark the tee with magic marker, as to which way it goes so if you take it off you can put it back on the correct way. If the gears shifted fine the rod should be good, but not sure about the bend. From the pictures of the adapter plate it looks like the plate might be exhaust cut some on the front where all the burnt black carbon is. Clean that area up real good and check for flatness of the plate. I use red silcone gasket sealer on the gasket when puting it back together as it is heat reistant. The plate can be cleaned and flatened by using a board with sandpaper wraped around it, just make sure that you use a circuler or fig. 8 motion and have the paper and board touching on the plate all the way accross while doing. When you put the motor back on the boat check to make sure that the cav. plate is even to 1/2" above the bottom of the boat.The bolts that you cannot use a toque wrench on ,you will have to do by hand. See how hard it is to pull one that is done and go from there. That should fix your problems. Check for water in the gear housing and repair now if it has much water in it. Best to do everything now and not have to tear everything apart latter.
Best of Boating
,Oldman570

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Cla4ressic

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Cla4ressic

Yeah I think you're right about it being the slinger seal - when I removed the lower unit the broken rubber ring fell out - I think it must have been an old one that got forgotten about or dropped on a previous impeller change as there is an intect slinger on the bottom of the driveshaft. What do you mean by "Needs the hose replaced from the cowl to the tee check valve" are you seeing a problem with the hose ?

Thanks for the advice will be sure to follow it.

One thing I have messed up though - hope you can help !!!!!!!!!!!!!

My engine is currently in bits i.e. all units still seperated - When I removed the shift shaft rod I accidentally rotated it - and can't even remember now in what direction. Now I dont know what gear the lower unit is in and in what position to insert the shift shaft when I refit it. Mine is the type with the splined male rod coming from the lower unit and the female splined socket on the bottom of the shift shaft.

What characteristics should the prop be displaying when in each gear ? - Sorry to ask the obvious

My Quicksilver commander 2000 is sitting in the neutral positon but I'm stumped - how do I know when the Lower unit is in Neutral and in what direction should I be twisting the spline to get it into neural also what position should I be inserting the shift rod ? I.e the triangular plate at the top of the shaft orientated how - for neutral ?????

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Cla4ressic

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Cla4ressic

Ok Got the lower unit into neutral - my lower shift shaft only has a bout 100 degrees of rotation I have found forward - neutral - reverse and forward again in that 100 degrees - all I really need to know is how to orientate the shift shaft - but I'm just realising it will be trial and error upon reassembling - with the Control in Neutral also - the arc shaped bracket coming from the shift cable pivot on the top end will only connect to the the pin on the triangular shift plate at one point of intersaction so it might take me a few tries to get it right. Am I on the right tracks ??

 

[oldman570]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Cla4ressic

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Cla4ressic

Your doing fine. I always put the LU in the Netural pos. along with the linkage up above when replacing the LU. I take the shift cables off the motor and mark one with tape so I get them back on the correct place when I have to put them back. In the photo from other post it looked like the fuel hose was bad. check the splins on the shif shaft and see if there is a spline that is larger or than the rest, if so it will have to mach up with the other coulping spline.
Oldman570

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Cla4ressic

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Cla4ressic

Will Do ! - Just waiting on Parts - Heres a couple of pictures - Used a piece of 3" CLS, 1/4" Ply and 4 Hardwood Wedges on each side to get the lower unit off - It just didn't want to go and then suddenly popped. Also a picture of my boat backed up into my shed.

http://flic.kr/p/byoLGB
http://flic.kr/p/byoLGv

Can't see any damage on the fuel hose - is it the one with white Tie Wraps or Black Tie Wraps ?

 

[oldman570]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

Your reply explains what I was seeing. It was the black tye wrap i was seeing and it appeared to be damage to the hose as the rest of the tyes are white. Sorry, I was looking fora white one or stainless clamp.
Oldman570:redface:

 

[murdmerc]

Re: Exhaust Smoke and Water Leak on Mercury 40 2-Stroke 4cyl 1991 Classic

Just an update for all

Engine now working fine - Reassembled and running. Replaced 2 upper and 2 lower mounts, gaskets, water pump serviced and also replace the 2 x upper mounts to steering swivel column seals which were the culprits for the exhaust smoke and water leaking.