Replacing rings in Johnson 70

I am told the rings need to be replaced in my 1987 Johnson 70 because it will not idle below 1200 rpm in gear. I was told its because of the rings & as I am not an outboard mechanic I really don't know. What I would like to know is what is a "reasonable & fair" price to have this done? I was quoted $1200.00 turn key job but have also been told that is "priced high". Does anyone have any knowledge about what is fair or high on doing a job like this?

I've already had the carbs rebuilt, complete engine tune-up, water pump & lower seals replaced & the engine runs very good above 1200 & doesn't skip a beat. I run it on my pontoon boat that is 24 ft weighing approx. 2300 lbs loaded & with GPS it says I am getting 17 mph @ 3800 rpm. It just won't idle like it is supposed to which I am told is around 900-1000 rpm. Any advice would be appreciated. Thanks

Re: Replacing rings in Johnson 70

It possible it needs more than rings due to this is the bridged exhaust block and are known to scuff pistons if lugged. Price is a little high for a re-ring and a couple hundred shy of a overhaul. How did they tell you they found problem? Was a leak down test performed? Was compression test OK as skirt and sidewall scuffing will not show up sometimes in a compression test.

Re: Replacing rings in Johnson 70

Faztbullet said:

It possible it needs more than rings due to this is the bridged exhaust block and are known to scuff pistons if lugged. Price is a little high for a re-ring and a couple hundred shy of a overhaul. How did they tell you they found problem? Was a leak down test performed? Was compression test OK as skirt and sidewall scuffing will not show up sometimes in a compression test.

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The compression test showed #1=123 #2=125 & #3=130. As far as a leak down test I am not aware that was done. After having the carbs rebuilt & the new water pump/impeller installed I took it out on the water for a test run. After the engine had warmed up & I put it in gear it died almost immediately. After several tries I got it to idle but not below 1200 rpms. I went back to the marina that did the work & the mechanic went out on the boat with me & tried to adjust the idle between 800-950 where he stated is should idle properly but it would not. The best it will idle at is 1200 rpms. he then told me it had to be the rings & it would cost $1200.00 to do the job. That is all I know about it at this time. I hate to put more money in the engine as it is nearly 24 yrs old but it runs great above 1200.

I'm thinking about buying a good used 1995 Evinrude 50 with only 20 hours of run time on it as the "need for speed" is not what I am looking for on my 24 ft. pontoon boat. Just wanting a good reliable engine that I can depend on that hopefully won't leave me stranded on the water. I'm not sure what my Johnson 70 will do right now. Thanks for the reply as I really need some good advice about this.

Re: Replacing rings in Johnson 70

Compression results don't even begin to suggest a need for any rings. I would look elsewhere (for a mechanic) and for the issue with idling. When were carbs last cleaned thoroughly (disaseembled, soaked, and all orifices cleaned)?

Re: Replacing rings in Johnson 70

wilde1j said:

Compression results don't even begin to suggest a need for any rings. I would look elsewhere (for a mechanic) and for the issue with idling. When were carbs last cleaned thoroughly (disaseembled, soaked, and all orifices cleaned)?

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I just had the carbs rebuilt along with a complete tuneup & new water pump installed June 2010. I also installed a water pressure gauge & new binnacle control too.

Re: Replacing rings in Johnson 70

i would 2nd the idea of getting a new mechanic. those compression numbers indicate the rings are just fine.

Re: Replacing rings in Johnson 70

The compression numbers are fine.....but they won't be for long if your maximum RPM is only 3,800, you should be turning 5,500 or higher at WOT. You need a prop designed to push a heavy load (less pitch).

Something else is wrong, clean the carbs and make sure everything is adjusted properly and it should run fine.

Re: Replacing rings in Johnson 70

When you try to get below 1200 does the motor slowly lose rpm and finally die? Or does it shut off instantly?

And yes, your top rpm should be way more than 3800......

Re: Replacing rings in Johnson 70

Since the carbs were worked on, was a proper link & sync done after they were installed. Unless timing and throttle linkages are synchronized and carbs set up properly it will not idle properly. You really need the help of a service tech -- not a dufus that calls himself a mechanic -- especially one that thinks those compression numbers point to a re-ring. Lastly, did this engine every run at 5000+ rpm wide open. If not, check the prop. If that engine was originally installed on a V-hull boat and the prop was not changed after the transplant, it is very likely this engine is being seriously lugged and it will eventually destroy itself. You need a pontoon prop which has much less pitch than one that would be used on a V-hull.

Re: Replacing rings in Johnson 70

Silvertip said:

Since the carbs were worked on, was a proper link & sync done after they were installed. Unless timing and throttle linkages are synchronized and carbs set up properly it will not idle properly. You really need the help of a service tech -- not a dufus that calls himself a mechanic -- especially one that thinks those compression numbers point to a re-ring. Lastly, did this engine every run at 5000+ rpm wide open. If not, check the prop. If that engine was originally installed on a V-hull boat and the prop was not changed after the transplant, it is very likely this engine is being seriously lugged and it will eventually destroy itself. You need a pontoon prop which has much less pitch than one that would be used on a V-hull.

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The 3800 rpms I gave was to show what the performance of the boat was at the rpm setting. When I first took it out I was running a 13-3/4X15 prop which only allowed me to get up to 4800 rpms maximum. I was told to go to a 13-3/4X13 as that would allow me to get a lot more rpms which in fact it did but I only got up to 5300. I bought another new 13-3/4X13 prop & had it modified to a 13-3/4X11 which I was told by the prop repair guy that it was considered to be what is called a "speed" prop & it should allow me to get around 55500-5800 rpms depending on the total load of the boat. I was running the 13-3/4X13 prop when I started having the idling problem & due to having eye surgery I have not been able to anymore to the engine & now it is far too cold to go out on the water. I live in VA & the weather is COLD & we are having lots of snow right now.

In answer to your question as to "has the engine ever ran at 5500-6000 rpms? NOT while I have had it. When I discovered all I could get using the 13-3/4 X13 prop was 5300 I throttled back to 3800 cruise speed instead as I was aware of what "lugging" an engine can do to it. A need for speed is NOT what I am looking for but I do want it to run correctly.

Its hard for me to believe my engine needs rings as good as it starts & runs once over 1200 rpms. As to the "sync" question I cannot answer that as I was not aware that was something that should have been done by the mechanic. He "IS" supposed to be a very good mechanic & was recommended to me by several people who have known him a long time. So that is all I know right now. I certainly appreciate the replies & all that I am learning at this time. Hopefully I can find someone who is honest enough to help me out with this engine. Any advice is greatly appreciated as I have learned a lot on this forum & I do a LOT of reading instead of posting.

Re: Replacing rings in Johnson 70

The dumbest questions I could ask here. 1, Is your tach accurate ? 2, Has anybody verfied your mtr rpm with a shop tach ? 3 How does it shift in and out of gear at the 1200 rpm ?

Re: Replacing rings in Johnson 70

boobie said:

The dumbest questions I could ask here. 1, Is your tach accurate ? 2, Has anybody verfied your mtr rpm with a shop tach ? 3 How does it shift in and out of gear at the 1200 rpm ?

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It shifts hard going into forward & reverse. In answer to your question about the tach, I have a brand new tach made by Teleflex LIDO series I bought from Iboats & as far as I know it is accurate. According to several people far more knowledgeable then I, they say it is very close to being correct. As for the shop tach being use I have no idea if one was ever used or not.

Re: Replacing rings in Johnson 70

The compression numbers are fine

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Compression numbers only tell you that the cylinders have pressure, they tell you nothing of condition. They are plenty of engines out there with good compression but worn out/damaged and all suffer the same plight..idle and fuel pump problems. From numbers posted # 1 is already lower than the rest. A quick check would be to pull head and inspect...