Evinrude 35hp +/-1980 missfire at higher rpm (lower cylinder)?

[Mapet]

Hi All,

I'm new on the forum but been reading it for a long time - it helped me a lot but now I need to ask for advice as I have enough and don't know what to do.

Short story:

I have bought old evinrude with several issues (I was thinking that engine is quite ok) and managed to get rid of most of them spending little fortune and a lot of time on reparation. It had very good compression on both cylinders.

Exhaust gasket below engine was blow out, stator was bad, coils and power pack etc.

I have changed this parts:

- new sparks

- new coils and power pack

- new exhaust gasket below motor

- new water pump

- new thermostat and gasket

- new stator and plate (bought used but in good condition)

- cleaned the motor, carb, checked fuel pump

- changed few gaskets - between fuel pump and engine, carb and engine etc.

- checked gas tank, cleaned it and put new gas

- changed fuel line

Most likely I've done more but forgot it already. I've set up carb and timing.

Motor works much better now but still not as it should. With low rpm it is ok but when I want to go faster and throttle starts to open more I'm experiencing most likely misfires - motor starts to shakes regularly and has no power. I can't go to WOT, not even to half open throttle. I've tried to squeeze fuel bulb to check if it caused by fuel pump but still the same. Motor is a bit hot, maybe even too hot - I still can touch the plate with the spark plugs for +/- 2s. It produces a lot of steam and when I start the motor for a first few seconds I can see exhaust fumes going out from water outlet. After few seconds water flows good. I got into conclusion that maybe there is a water going into one of the cylinders at higher rpm and took the exhaust plate out and power head to check the gaskets. All were looking ok in my opinion but the exhaust manifold? looks a bit weird - it is obvious that bottom cylinder produce more carbon muck and also had a white stuff around the lower exhaust port. Cylinders gasket was fine with no signs of bad sealing. Could you please take a look on the attached pictures and share your thoughts? Any ideas what could be wrong with the motor and what should I check and do to finally enjoy fishing?

Best Regards.

 

[saltchuckmatt]

Hi All,

I'm new on the forum but been reading it for a long time - it helped me a lot but now I need to ask for advice as I have enough and don't know what to do.

Short story:

I have bought old evinrude with several issues (I was thinking that engine is quite ok) and managed to get rid of most of them spending little fortune and a lot of time on reparation. It had very good compression on both cylinders.

Exhaust gasket below engine was blow out, stator was bad, coils and power pack etc.

I have changed this parts:

- new sparks

- new coils and power pack

- new exhaust gasket below motor

- new water pump

- new thermostat and gasket

- new stator and plate (bought used but in good condition)

- cleaned the motor, carb, checked fuel pump

- changed few gaskets - between fuel pump and engine, carb and engine etc.

- checked gas tank, cleaned it and put new gas

- changed fuel line

Most likely I've done more but forgot it already. I've set up carb and timing.

Motor works much better now but still not as it should. With low rpm it is ok but when I want to go faster and throttle starts to open more I'm experiencing most likely misfires - motor starts to shakes regularly and has no power. I can't go to WOT, not even to half open throttle. I've tried to squeeze fuel bulb to check if it caused by fuel pump but still the same. Motor is a bit hot, maybe even too hot - I still can touch the plate with the spark plugs for +/- 2s. It produces a lot of steam and when I start the motor for a first few seconds I can see exhaust fumes going out from water outlet. After few seconds water flows good. I got into conclusion that maybe there is a water going into one of the cylinders at higher rpm and took the exhaust plate out and power head to check the gaskets. All were looking ok in my opinion but the exhaust manifold? looks a bit weird - it is obvious that bottom cylinder produce more carbon muck and also had a white stuff around the lower exhaust port. Cylinders gasket was fine with no signs of bad sealing. Could you please take a look on the attached pictures and share your thoughts? Any ideas what could be wrong with the motor and what should I check and do to finally enjoy fishing?

Best Regards.

Never did a compression check? Steam.... exhaust out TT? blown head gasket maybe?

 

[Mapet]

Never did a compression check? Steam.... exhaust out TT? blown head gasket maybe?

Hi, thank you for reply. As mentioned in the post I`ve checked the compression and was good on both cylinders (125 and 123psi if I remember correctly). Not sure what "TT" means. I have changed exhaust gasket between block and leg as it was blown out. Head gasket I checked two days ago and it was looking great (pictures are attached to the post).
Regards,
Maciej

 

[tphoyt]

TT is short for tell tail.
Did you do a link and sync went you put her back together?
Have you looking into the possibility of losing spark in one cylinder while under way? You can check for that with a timing light hooked up if you have one handy.

 

[saltchuckmatt]

Hi, thank you for reply. As mentioned in the post I`ve checked the compression and was good on both cylinders (125 and 123psi if I remember correctly). Not sure what "TT" means. I have changed exhaust gasket between block and leg as it was blown out. Head gasket I checked two days ago and it was looking great (pictures are attached to the post).
Regards,
Maciej

You said you saw exhaust out the water hole (TT)

Exhaust should not come out there. Also, head does not look good to me. Pictures are before you cleaned the up I take it.

You need to clean, inspect/flatten and reinstall a new gasket.

Do you know how to resurface a head?

 

[Mapet]

TT is short for tell tail.
Did you do a link and sync went you put her back together?
Have you looking into the possibility of losing spark in one cylinder while under way? You can check for that with a timing light hooked up if you have one handy.

I`ve got good water flow from TT all the time, thermostat works as it temperature is cold - warm - cold- warm etc. Steam which I`m talking about is getting out from two holes on the leg sometimes - i.e. when I stop after going for a while.

I have done link and sync by setting up carb - low rev adjustment and throttle plate starts open when roll is passing signs. I`ve got the timing light (not a fancy one) but I will try when I put everything back togeather. I had hoe that all should be fine with sparks as I have changed almost all components in the ignition system - plugs, cables, coils, power pack and stator but it is good idea to double check with the light.

What I`m wonder about the most is a white stuff in exhaust manifold close to the lowest exhaust port on lower cylinder. Is that normal or is it a sign of water?

 

[Mapet]

You said you saw exhaust out the water hole (TT)

Exhaust should not come out there. Also, head does not look good to me. Pictures are before you cleaned the up I take it.

You need to clean, inspect/flatten and reinstall a new gasket.

Do you know how to resurface a head?

Yes, I can see exhaust fumes going out from TT but only a few seconds after starting engine and good continous stream after.

It is a good news for me that head doesn`t look good for you I`m not mechanic and it is my first project on the outboard engine - as metal rings were fine I would assume all good on head gasket

I will reinstall head and exhaust plate gaskets as I damaged them doing investigation. When changing gaskets before I was using razor blade and very fine sandpaper but will check youtube for head gasket replacement to make it in a proper way.

Thank you all for answers!

 

[tphoyt]

I’m assuming you have this motor back together as you said it’s running better. Did you reuse the head gasket or replace it? Some will disagree but in my eyes head gaskets are a once an done gasket. Once they are compressed they won’t seal properly again.

 

[saltchuckmatt]

Yes, I can see exhaust fumes going out from TT but only a few seconds after starting engine and good continous stream after.

It is a good news for me that head doesn`t look good for you I`m not mechanic and it is my first project on the outboard engine - as metal rings were fine I would assume all good on head gasket

I will reinstall head and exhaust plate gaskets as I damaged them doing investigation. When changing gaskets before I was using razor blade and very fine sandpaper but will check youtube for head gasket replacement to make it in a proper way.

Thank you all for answers!

Yes, new gaskets for sure.

But you need to make your head flat again. Sand paper on a piece of glass or counter top piece. Has to be dead flat. Take your head and do figure eight motions on it. I use 220 wet but people seem to use all kinds of grits.

 

[racerone]

A 40 year old aluminum casting will be warped !!----Needs to be trued up !!

 

[kbait]

If nozzle gasket in carb is missing, motor will run exactly as you describe.. Bogs/dies above 1/4 - 1/3 throttle.

338881​

 

[Mapet]

Thank you all for answers
I will do as you advised - plan/flatten head and change all gaskets to the new ones. I will take a look into carb again to check if there is a gasket mentioned above.

Could you advise what torque I should apply to the bolts on the head and which order? Same question for a exhaust cover plate.

In one movie on YT I`ve seen that someone sprayed head gasket with some polymer prior installation - should I do the same or install it dry?

I need to order and wait for parts but will keep you updated.
Regards,
Maciej

 

[saltchuckmatt]

Thank you all for answers
I will do as you advised - plan/flatten head and change all gaskets to the new ones. I will take a look into carb again to check if there is a gasket mentioned above.

Could you advise what torque I should apply to the bolts on the head and which order? Same question for a exhaust cover plate.

In one movie on YT I`ve seen that someone sprayed head gasket with some polymer prior installation - should I do the same or install it dry?

I need to order and wait for parts but will keep you updated.
Regards,
Maciej

18 ft pounds on the head bolts starting in the middle and working outward in a x pattern.

I don't use anything on the head gasket but perhaps others do.

After you flatten the head out make sure to clean it very well. No fine metal shavings can go into the motor.

 

[Mapet]

Thank you,
I finally got ordered parts
I have new head gasket, two exhaust cover gaskets, rebuilding set for fuel pump and carb.
I will make some pictures from repair and post here to keep you updated. I will also write something after checking engine on the water.
Regards

 

[saltchuckmatt]

Thank you,
I finally got ordered parts
I have new head gasket, two exhaust cover gaskets, rebuilding set for fuel pump and carb.
I will make some pictures from repair and post here to keep you updated. I will also write something after checking engine on the water.
Regards

Ok, lots to do. Good luck!

 

[Mapet]

Thanks.

Quick update - I had to take powerhead off to have better access (one bolt in exhaust plate broke and stuck) and to torque everithing up after repair. I have done it to take a look into exhaust itself and investigate from where this wite stuff which I mentioned in the first post is comming.

I have found that exhaust gasket which I have changed few months ago was ok and no signs of leakeage, but I am a bit confused with exhaust itself now.

I found that there is a hole through the exhaust and I believe that is cousing problems as white stuff - salt was around it and seems to be sucking into lower cylinder. I`m not sure if the exhaust is as it should be for this motor or if it has been changed in the past for the one from different model. I went through pictures on google and found that in fact it should look slightly diffrent and there is no such a hole in in. Please share your thoughts and advise.

Pictures attached.
Best Regards,
Maciej