Merco 61 Twin Plug Strip Down

[Rich Griff]

You have seen the merco marine 61 parts exploded view sheet I posted some time ago ?

 

Print it off for future reference.

 

Nicely gummed up engine.

 

I use hot oil to free off engines, heat and desolves  the caster gum a bit.

 

Fuel, meths and petrol are good for cleaning castor gum etc. But do it outside !!!

 

Have a fire extinguisher at hand !!!

 

I use small quantities, 1/4 of a litre or less, but it's still a very real fire risk.

 

I also soak the parts over night in a suitable container with a lid. The "cleaning fluid" can be filtered and re used until spent.

 

I have some further info in a ripmax catalogue, but must crack on with domestic and car stuff, but can post again this evening.

 

Take your time and enjoy.

 

Ps don't know if petrol kills glow plugs, you have seen the reaction between unpowered glow plugs and methanol ?

 

They do react with each other, a further fire risk.

 

You have been warned !

Edited February 1, 2022 by Rich Griff

[PatMc]

2 hours ago, Robin Colbourne said:

 

1. What threads is this engine likely to use?  I've tried what I think are M3 and 6BA, but neither seem to want to go in.  The only review which mentions these threads is the one on the late Premier-made Merco 61 which were M3, but I guess by the time they were made, older sizes of production taps may have been getting expensive or difficult to obain.

 

I once had to change a couple of damaged head screws on a twin plug Merco 61 & could not determine the thread so drilled 4BA for all the screws then used 4BA Allen studs.

I later  discovered that the originals were 1/8" Whitworth which is (or was) a popular thread with model engineers. 

[Andy J]

Think your engine interior resembled mine Robin, but don't think the glow plugs are the original ones as seem to recall in the 70's all the Mercos used a round head ball type which was more compatible with the old style glow clips.

[PatMc]

I don't think production Mercos were ever supplied with the ball head type plugs (KLG?) except possibly a few of the early stunt 35's.

In fact were the ball head plugs still being produced beyond the late 50's ? IIRC the Merco 49's & 61's weren't in production until around 1962 & 1964 respectively.

[Robin Colbourne]

Rich, Pat & Andy, thank you for the replies.
 

Rich, yes I did see the Merco exploded diagram, however I couldn't read the writing on it.  I will take care with cleaning.  I doubt small amounts of petrol would damage glowplugs, as Merco recommend adding 5% petrol to ordinary glow fuel to improve starting and throttling.
I'll probably give my as yet untested ultrasonic tank a try.  What we used to do at work if something was really grubby, was to put the solvent and part to be cleaned in a glass jar, and then put that in the tank surrounded by clean solvent or just water.  By doing this, only a small amont of solvent would be made dirty.

Pat, I hope you are right, as 1/8 Whitworth shouldn't be a problem.  Dad did his apprenticeship at Short Brothers in Rochester at the end of the war, converting miltary Sunderlands into civil Sandringham airliners.  1/8" Whitworth screws were used in lieu of Cleco fasteners to hold parts together before riveting.  After removal they were thrown on the floor and swept up by the cleaners.  Dad must have intercepted quite a few on their way to the bin and there is a jar of them somewhere if only I can find it.

Andy, I have some of those ball-headed glowplugs, but hadn't made the link to them being Merco.  As far as I can see, all the Merco 61 tests on Sceptreflight use conventional looking plugs.


 

[Robin Colbourne]

PatMc, this Merco 35 test refers to the ball-headed plug as being KLG  Merco 35 Engine test with KLG Plug

 

There is always the possibility that Merco sold them at some stage marked up as their own.

I've just read in that Merco 35 test that it was run in on fuel with 30% castor oil.  We had better not tell Jon@Laser engines!

Edited February 1, 2022 by Robin Colbourne

[Rich Griff]

If rapid electronics can supply a 15v 3a voltage regulator I can get the scanner operational and scan that merco parts sheet as well as merco and Enya ( Sosam, coxmodelengine forum, well worth a look see ) info in a 1978/79 Ripmax modellers handbook, then go to library ( no land line or internet capable pc ) for my 45mins per week, as long as I pre book, internet session, I can post on here .

 

I have seen a klg glow plug advert somewhere that had a ball end.

 

In the ripmax handbook, the merco brand of glow plugs don't have ball ends.

 

Merco parts with numbers etc. are listed in the ripmax handbook, as well as pictures and descriptions of merco engines of the time/era.

 

An interesting read.

[Rich Griff]

Yes, a jar with a wide enough neck for a merco 61, large Nescafé jar, you can see the "bits of gum" floating about.

 

Easy to agitate the engine parts and fluid.

 

Salsa type low jar for smaller engines and Cox.

 

I bought a small saucepan especially for model engine heating in oil and cleaning.

 

Much more convenient than the old large saucepan scrapped by the cooking staff.

 

You can only get away with setting the sprouts ON FIRE once, no matter how many times she tries.....long story and true.

[PatMc]

2 hours ago, Robin Colbourne said:

PatMc, this Merco 35 test refers to the ball-headed plug as being KLG  Merco 35 Engine test with KLG Plug

 

There is always the possibility that Merco sold them at some stage marked up as their own.

I've just read in that Merco 35 test that it was run in on fuel with 30% castor oil.  We had better not tell Jon@Laser engines!

Robin, this Merco 35 test in the AM a month later than the MA test mentions comparing results using KLG & A-M (Alan Mercury ?) plugs but carries out the test using the latter. 

Note - Warring carries out the actual test using an even higher castor content fuel than the 30% castor Chinn used for running in !!!!!

 

Bearing in mind that at the time the main use of any 35 engine was for C/L stunt the results of these tests were pretty useless, the actual max power output was academic to us. It was more important that the engine that could be relied on to run rich enough to 4 stroke when flying level but break into 2 stroke running & back to 4 stroke again as required in order to maintain constant speed during manoeuvers.

 

 

 

[PatMc]

Oops, I forgot to insert this link to Warring's Merco 35 test.