Decarb - Heads Off

[urugol]

Ok I have read all about decarbing with seafoam and engine tuner etc, I'm wondering if anyone has any experience doing it with the heads off? I removed the heads of a newly acquired 115 Ficht and the carbon build up is on the extreme side. What I intend to do is clean the head domes with carb cleaner and a soft wire brush, which I will probably do with the piston domes in the top position also. What I'm wondering is how I go about cleaning the cylinder barrels (don't think wire brush is a good idea) and unsticking the piston rings. I am certain that at least 2 of these pistons have carbon stuck rings as my comp readings are all over the place. When I manage to wipe enough carbon with a clean rag I get a nice crosshatch revealed with no scoring marks so I know this engine is good. Any advice here appreciated. I removed the heads to ensure there was no real damage, glad to see that is the case.

Pics attached!

 

[HighTrim]

Re: Decarb - Heads Off

You can try it like that, but as far as freeing up stuck rings, I have found it best to use the Seafoam on a running engine.

 

[boobie]

Re: Decarb - Heads Off

Agree + 1 !!

 

[Faztbullet]

Re: Decarb - Heads Off

Putting Seafoam in the fuel on a ficht wont clean much of the rings due to its squirted into pocket in piston, you would be better off to spray Engine tuner thru the throttle bodies as this will get to the rings for sure...

 

[urugol]

Re: Decarb - Heads Off

Putting Seafoam in the fuel on a ficht wont clean much of the rings due to its squirted into pocket in piston, you would be better off to spray Engine tuner thru the throttle bodies as this will get to the rings for sure...

Thanks, I will do that as soon as I get it back together - first I am removing everything with good old elbow grease. I have done one side of the pistons and heads, I'm thinking I may pull the intake to inspect the reeds and maybe I can hit the rings with carb cleaner through the intake as they will be visible and I can confirm if they are stuck or not (which I believe they will be).

 

[phillnjack2]

Re: Decarb - Heads Off

Well being as the heads are off and your gonna take the intake off, why not pull the pistons out and do it properly.
Once the pistons are out on the bench youl be able to see more of whats going on and be 100% sure.
Just dont go breaking the rings if they are good, but while out you could just simply put new rings in and do a break in for a
few hours, this could save you a fortune in the long run.
Coz if you suspect sticky rings and they dont get completely cleaned you could end up with a broken ring and who knows
what amount damage can be done.

i have used quicksilver power tune in the past and when i did pull a head one day, i couldnt believe how clean it was,
the piston crowns were like brand new as well.

But if its already got the heads off i would just check the pistons with them out on the bench.

Just my opinion

phill

 

[trendsetter240]

Re: Decarb - Heads Off

I agree with the above but from heads off to pistons out is a long way on that motor. What were the original compression readings?

P.S. do not take a wire brush to the cylinder bore.

 

[CaneCutter79]

Re: Decarb - Heads Off

I have learned so much in the last few years here on iboats thanks to all of the helpful members.

I just got my motor back from a full rebuild. I too took the heads off by couldn't see the hole in the piston or the fact that the rings were stuck in so tight you would have to soak them for days to break them lose. That and after 33yrs, I needed new rings.

The cylinder wall is a very delicate thing. Do NOT scratch or use a wirebrush on the cylinders! That will totally trash the cylinder wall.

Take the motor apart if you have a repair manual bad know outboards well. If not, take it to a mechanic and have him rebuild it. If the rings are stuck , they will cause more damage. Take it from someone who just went through very similar scenario. I took my heads off and thought I had solved my issue. I didn't. Pistons got worse, scored the cylinder wall and I had to re-sleeve the cylinder.

I have 4 beautiful new Wiseco pistons in my motor, factory bores, and the motor is running good now. Better than ever.

Save the frustration and pull the pistons. Don't chance it. You probably need new rings. If your compressions is still high and in spec range, soak it with seafoam for a few days and turn the motor by hand. Resoak every few hours and turn the motor. Then....shoot it into the Carb with motor running and after the smoke clears.....run the motor for a little while and check compression. More than likely you won't see much improvement. If its as carved up as you described. .....pull the pistons. Do it right. Save some money
Save some headache.

 

[CaneCutter79]

Re: Decarb - Heads Off

*carbed up*....not carved

 

[urugol]

Re: Decarb - Heads Off

Thanks for all the input. No chance I will be taking a wire brush to the cylinder walls

I have a fair amount of experience working on Ficht injected jetskis, and while I agree 100% in pulling the pistons, changing rings (heck they cost about the same as 2 cans of engine tune), as another poster mentioned here I'm pretty far away from such a task. To pull the pistons requires pretty much complete powerhead disassembly if I'm not mistaken, while I haven't done it before I am comfortable doing it but it will be fast to try this first - if comp doesn't improve I will do a complete tear down, re-hone, re-ring. On the Jetski engines it would be no problem as each cylinder comes off with 4 bolts, actually they can be re-ringed without removing the piston from the rod. So I'm trying to get as much of this carbon out as possible before running it with engine tuner to hopefully unstick the rings. The bores look really good there is a tiny score just above one of the ports, I would love to hone it but it is really minimal and should not affect my readings. Interestingly, one of the pistons was so carboned up it was starting to pit all of that junk against the head.

My initial readings were 150/120 on the Starboard and 150/110 on the Port side. The low comp cylinders correspond with the most carbon, the intake and exhaust is covered with the stuff.

 

[CaneCutter79]

Re: Decarb - Heads Off

Hard to tell from the photos but it appears one of the cylinders is “glassy”. If it’s glazed over and really smooth, it’s too late.

Also, from what I learned in my rebuild and compression issues I was having, compression should not be more than 10%(?) difference between each other. You have a difference of 150 to 120 which is a 20% difference. I’d say it’s going to drop even more over the next few times you run it. That’s what happened to mine. My cylinder also had a score mark that didn’t look that bad but it was bad enough out of spec that the machine shop said “sleeve it”.

I understand completely about being hesitant on doing a breakdown. I was too. After I read my manual, it didn’t look that bad but there were a lot of things I didn’t understand or know about. There are lots of folks here that can help you out. If you have the time and the space to work on such a project and you want to save the money, try doing a teardown with some help from the forum. There are many guys here that can walk you through it. If you’re in a hurry or don’t mind spending the money, have it rebuilt. You get a warranty with the rebuild. Find a mechanic that is highly recommended and reasonable on price. I did. I had to drive 4hrs but it was well worth it.

That really is a lot of carbon build up. I’m thinking Seafoam will meet it’s match. That’s my hunch anyway. Let us know how it turns out and good luck. (I’ve been there…..don’t want to go back either)

 

[urugol]

Re: Decarb - Heads Off

I think the comp readings will rise if i get the rings unstuck. Having said that there is some scoring right above the intake port on one cylinder, it's not too bad but might just be bad enough so I may ultimately need to tear the whole thing down. I estimate that at worst a full top end rebuild will set me back around 5 benjamins. Could be less depending on whether a hone will suffice, and a new set of rings provided the ring gap is within spec. Out of interest, what is the typical lifespan for a crank on these outboards? This machine has run for 1,200 hours now but it has spent 70% of its life doing 1,000 rpm.

 

[Faztbullet]

Re: Decarb - Heads Off

but it has spent 70% of its life doing 1,000 rpm.

The cause of the carbon build up... likely using standard 2 stroke oil instead of the DI oil too.

 

[CaneCutter79]

Re: Decarb - Heads Off

I think you will be surprised on cost. Might want to re-check. My rebuild was closer to $800 in parts alone. May have been more.

I doubt the rehone will remove the gouge. That was my experience. It will only remove the glossy finish and small scratches. If its a "gouge", its a resleeve. Just don't want you to get your hopes up like I did. My resleeve was about $50 more so I got a great deal. For the price you pay for a rebuild....resleeve it without thinking twice. Beats having to tear it down again which is more than the cost of a resleeve.

My rebuild was around $2,500. Just to give you an idea on cost. It varies depending on mechanic but I would say this is the low average. I have a 15mo warranty for parts and labor.

 

[urugol]

Re: Decarb - Heads Off

I will do the work myself. I figure worst case if I need to do all 4 (which I don't) I'm looking at $380 for the Wiseco piston kits. I can get a rebore and hone of all 4 cylinders for around $200 at an engineering shop that I have used before over here as well. Then I need some new o-rings for the head, cylinders and thermostat that's another $50 and whatever a new powerhead main gasket costs and a tube of 1211 so around $700 worst case I think. Of course this all depends on how good my crank is as well but I don't really want to think too much about that. I don't think sleeving avoids a tear down in the future, you still need to tear down the engine to press a new sleeve so I'm not sure what you mean by that? That you don't need a rebore?

I have read a bit about DI oils and agree it's a very likely cause to use standard tcw3. It's hard to find the Evinrude XD50 or XD100 stuff out here, but I have been using a fully synthetic ashless formula here on my DI jetski with excellent results and that uses the same ficht injectors so I might stick to that for the boat.

 

[trendsetter240]

Re: Decarb - Heads Off

If you do decide to do the complete rebuild, do the complete teardown of the power head before you buy any new parts.

When everything is apart you need to examine the crank for damage and check the journals to see if they are within wear tolerance. Also you need to examine all the bearings (crank mains, lower crank, connecting rod, top end needles etc). If the crank or bearings need replacing add that to the cost.

Then take the block and heads into the machine shop and find out what can be done; whether it's a bore on one or more cylinders, just a hone or if you need some new sleeves. Also the heads should be checked for warpage as well.

Finding other parts to be replaced might change your mind so leave the part purchasing until last.

Cheers

 

[CaneCutter79]

Re: Decarb - Heads Off

I I don't think sleeving avoids a tear down in the future, you still need to tear down the engine to press a new sleeve so I'm not sure what you mean by that? That you don't need a rebore?

You misunderstood me. You WILL have to tear down to get the block out in order to resleeve. Take the powerhead (block) to the machine shop and they can measure the cylinder for squareness and bore. If the re-hone will not remove the gouge (what happend to me), they will need to resleeve or bore the cylinder. Then you would need oversided cylinders if they have to bore the cylinder.

 

[urugol]

Re: Decarb - Heads Off

So I put the heads back on today to see if my effort worked. I succeeded in unsticking the rings using this method, and I now have 155 psi even on 3 of my 4 cylinders. Unfortunately, the one that is slightly scored is coming in at 110psi. I can lift it to 125 if I pump a bit of oil down the cylinders but it looks like I will be doing a teardown after all. I will get the one cylinder bored hopefully one size up should do and the others I will get honed. New rings all round and back together she will go. While I'm down there I will also replace any crank seals and bearings.

 

[CaneCutter79]

Re: Decarb - Heads Off

Its like I'm reading my own history. Sounds just like what happened to me.

Sorry to hear about the tear down but your ring is blown on the bad cylinder and may have a hole in it. You're better off with the tear down.

 

[Faztbullet]

Re: Decarb - Heads Off

If you do the rebuild do not go over .030 as you cannot richen up the cylinders due to its a DI motor. Also I advise not to use forged pistons in a DI due to the engine runs so lean to meet emissions. Take a ton of pictures of wiring and fuel system layouts as the wires/harnesses/fuel plumbing have to be installed a certain way. Make sure you install all the grounding washers correctly(star washer) and in same place removed,replace upper seal and lower seal housing,upper and lower crank bearings, gasketss and filters. If you have to bore over .030 it will need resleeved and the pistons are $78 each