Robin Engine 500 Hour Maintenance

[BobRip]

I am at about 480 hours on my PT422 Robin Subaru Engine. (Yes, I know I have discussed this before, but could not find the posting). The recommendation is to clean the heads of carbon and adjust and check valve seats at 500 hours. I have seen some recommendations to spray water into the intake to clean carbon out. Does anyone have experience doing this? Is there a risk? Is it really effective on an air cooled engine?

I was all set to start working on the head removal. I looked at what it takes to remove the heads and it looks like you have to pull the engine to remove the intake manifold and then pull the heads. I am reluctant to do this. I don't want to be lazy and not do routine maintenance, but the engine is running great and I hate to mess with it.

Jack Robin, your comments as always would be apprecaited.

Bob Rip

 

[pajoube]

You sure have put the hours on in a very short time.
That is the first I have heard that you would remove the heads to work on them. Is everything working well? If so then I would leave it alone.
PJ

 

[BobRip]

In the back of the Service Manual it has a table for the maintenance. It says "clean heads". Maybe I have misunderstood this. Perhaps it just means clean the outside. However I got the impression from Jack Robin that this is really needed and its carbon on the inside. Let's see what others say. It also says "check and adjust valve seats" and adjust valve clearance. I will adjust the valve clearance.

I have had the machine since 2000, so that's about 100 hours a year. I do play with it a lot and help the neighbors a fair amount.

Bob Rip

 

[DHS]

I checked my 422 valve adjustment at 300 hours and they were off considerably. Adjusted to spec and the engine starts better and runs better. A couple times a year I add a few onces of Sea Foam to the gas tank. Sea Foam is suppose to help clean the carbon from two cycle engines. Since it works well in my boat motor I assume it helps remove carbon from the heads of my Robin engine.

Dale

 

[toolz_not_toyz]

</font><font color="blue" class="small">( Sea Foam is suppose to help clean the carbon from two cycle engines. )</font>

Errrr. Your PT has a 4 stroke engine. /forums/images/graemlins/smirk.gif

 

[DHS]

Errrr. Your PT has a 4 stroke engine. <font color="blue"> </font>

So, do you not believe Sea Foam can help remove carbon from a four stroke? Do you believe Sea Foam could be harmful to a fourstroke engine? I have not yet been able to definitively determine the effectiveness of Sea Foam. I have been using it for ten years in my boat, Honda four strokes and my Robin engine. I have been patiently waiting for one of them to break so I can open it up to check the carbon deposits.

Thanks

Dale

 

[BobRip]

Which is worse, sea foam or water? Thanks for having the heated discussion, so I don't have to.

And really thanks for all of the comments.

Take care, but not all of it.

Bob Rip

 

[MossRoad]

<font color="blue">I have been patiently waiting for one of them to break so I can open it up to check the carbon deposits.
</font>

If you keep taking care of them, you may never get to look inside one. /forums/images/graemlins/wink.gif

I have a 1985 Craftsman lawnmower with a 3.5HP Briggs. I have never changed the oil, air cleaner or spark plug. It still starts and runs. I just top off the oil when needed. I've been waiting for 20 years for this thing to croak so I can get a better push mower, but no luck! /forums/images/graemlins/tongue.gif

 

[DHS]

"Thanks for having the heated discussion, so I don't have to."

I certainly didn't intend to heat up the discussion. My intent was to provide alternative thoughts. Since my PT will cross 500 hours next summer I am interested to discover how others have removed carbon from their Robin heads. Since Robin has a two year warranty and my PT is four years old, I am most interested in what is necessary and what actually works.

It would be nice to have input from Jack at Robin.

MossRoad may have the secret to engine longevity. /forums/images/graemlins/wink.gif

Thanks

Dale

 

[tracdoc]

This discussion piqued my curiosity about SeaFoam. I must admit that I had never heard of it until reading this thread. On looking up the MSDS for SeaFoam, it is a mix of non-polar (hydrocarbon) and polar (water miscible) compounds: pale oil (?), naphtha (aka lighter fluid), and isopropyl alcohol (aka rubbing alcohol) in the approximate proportion of 6:3:1.

The isopropyl alcohol mixes with the hydrocarbon components because the ends of the molecule are non-polar. The polar hydroxyl group (-OH) in the middle of the molecule wets/solubilizes the carbon deposits which are then carried through the combustion process. Unlike a lot of the "snake oil" products out there, SeaFoam appears to be rationally formulated. The mfr indicates {SeaFoam website} that it can be used in 2-stroke, 4-stroke, and diesel engines, both in the fuel and in the crankcase immediately prior to an oil change.

Keeping in mind that I have no personal experience (yet) with SeaFoam, one approach might be to use a SeaFoam fuel treatment followed by a SeaFoam oil treatment, change out the oil and then do a valve clearance check/adjustment, i.e., clean out the carbon and then adjust the valves. Valve adjustment "should" be do-able by removing only the valve covers (Fig 5-39, p.39 in the pdf format Service Manual) or per the competition's guide {HERE}

 

[MuncyBob]

I also never heard of SeaFoam...did a little searching in Google Groups and many people say it does wonders on cleaning up any gum or carbon in engines......but I would like to hear from experienced mechanics on ANY additive before I use it.

 

[J_J]

My opinion is, if it ain't broke, don't fix it.

Read this and see if it will help.

10. Remove carbon deposits. An accumulation of carbon deposits in the combustion chamber and on the top of the pistons can increase compression to the point where detonation becomes a problem. Carbon deposits are a common cause of detonation in high-mileage engines, and can be especially thick if the engine consumes oil because of worn valve guides and seals, worn or broken piston rings and/or cylinder wear. Infrequent driving and not changing the oil often enough can also accelerate the buildup of deposits.
In addition to increasing compression, carbon deposits also have an insulating effect that slows the normal transfer of heat away from the combustion chamber into the head. A thick layer of deposits can therefore raise combustion temperatures and contribute to "preignition" as well as detonation.
Carbon deposits can often be removed from an engine that's still in service by using a chemical "top cleaner." This type of product is poured into an idling engine through the carburetor or throttle body. The engine is then shut off so the solvent can soak into and loosen the deposits. When the engine is restarted the deposits are blown out of the combustion chamber.
If chemical cleaning fails to remove the deposits, it may be necessary to pull the cylinder head and scrape the deposits off with a wire brush or scraper (be careful not to scratch the face of the cylinder head or engine deck

 

[Charlie_Iliff]

<font color="red"> Carbon deposits can often be removed from an engine that's still in service by using a chemical "top cleaner." This type of product is poured into an idling engine through the carburetor or throttle body. </font>
Ordinary water works great for this. And it puts out wonderful amounts of steam through the exhaust. Of course, no engine I've ever taken apart needed the treatment unless it was burning ungodly amounts of oil before the teardown. But it sure was satisfying first to make an impressive steam claoud and then go out and drive at highly illegal speeds to "blow out" the rest of the carbon. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[FOURTEEN]

</font><font color="blue" class="small">( An accumulation of carbon deposits in the combustion chamber and on the top of the pistons can increase compression to the point where detonation becomes a problem. A thick layer of deposits can therefore raise combustion temperatures and contribute to "preignition" as well as detonation.)</font>


<font color="red"> Perhaps, but if the oil is changed regularly, and there are no signs of detonation or preignition, why waste money on solving a problem that apparently does not even exist!! Every engine manual says to use no additives. Dumping water into a running engine doesn't even sound right, and too much at once could destroy the engine! Maybe Robin is fishing for an extra service charge!!??!!
A small increase in compression will actually increase power, and a thin carbon coating can protect the top of the aluminum piston.
After 22 years my Kohler blew a head gasket. The combustion chamber was in fine shape with just a paper thin carbon coating. I just reinstalled the head with a new gasket and it has run great for the last 7 years!
Check the spark plugs. If they are clean, or only lightly coated, the combustion chamber should be fine. If the plug is burned, or heavily coated, or soaked with oil, then you indeed have problems, and it may be time to install a Kohler or Honda!!

</font>

 

[J_J]

I am just so happy for you , that your machines never have any problems.

Read the first line in my post. I didn't say do anything to the engine. This data came from an article written by someone who I believe has a little more knowledge than you are me. This was for info only. You need to get a grip on life and not be so negative on everything. If the water thing works for someone, so what. I am sure that did not mean to imply that they dump gallons of water into the carb to flush out the offending carbon. In fact a water mist has been used before to help clean the combustion chamber. If someone wants to clean the carbon from the heads, so what.

Your reply to carbon on the piston is a good thing is totally wrong. What do you think burns holes in piston heads, hot spots in the carbon, is just one thing. A good running engine usually doesn't leave a lot of carbon in the cylinder head and or on the piston.

It's not what you think that counts, it's the facts of life that are proven over and over.

 

[Gravy]

</font><font color="blue" class="small">( I also never heard of SeaFoam...did a little searching in Google Groups and many people say it does wonders on cleaning up any gum or carbon in engines......but I would like to hear from experienced mechanics on ANY additive before I use it.

Gravy

 

[MuncyBob]

I heard of adding a SMALL amount of water into a running vehicle that has a carb a long time ago from several race car drivers. It's always sounded a bit extreme to me but they swore by it..I've never actually tried it but still it sounds interesting.

 

[J_J]

Here is another article about water injection, believe it or not.

Water injection also has the effect of "steam cleaning" the combustion chambers and exhaust valves. This removes the carbon build up that decreases efficiency and leads to pre-ignition(detonation). It will also keep the throttle body and interior of the intake manifold much cleaner than normal.

 

[MossRoad]

<font color="blue"> drive at highly illegal speeds to "blow out" the rest of the carbon. </font>

I actually remember when a cop would laugh and let you go if you were just blowing out the carbon... as long as there wasn't another car next to you doing the same thing on a nice, long stretch of two lane! /forums/images/graemlins/wink.gif Then it was eight points and a talk with your folks. /forums/images/graemlins/shocked.gif

 

[Charlie_Iliff]

The water I referred to above was simply poured through the carburetor of a running engine. You have to keep the revs up, of course, or it drowns it. It does a very good job of carbon removal, but I doubt it or any other carbon removal is necessary as routine maintenance on Robin or Kohler PT engines.
Water injection is good to avoid detonation in blown race engines, and there are volumes of debate about whether the water itself boosts usable power. I'm in the negative on that one, but it definitely allows you to use more boost and more ignition advance before the inevitable expensive failure. /forums/images/graemlins/tongue.gif