2.5 was stored for several years using cartor oil-trouble!

[d&smach]

The title shoud have read CASTOR oil, I wasn't able to edit the title. I have four 2.5's that sat for a few years after using castor oil. They were very hard to turn over and a good shot of wd-40 in the cylinders enabled three of them to fire up. Before starting the compression was horribly uneven from 45 psi to 165 in various cylinders. All of the first three after starting and running for several minutes to full warm up came back beautifully. very high and even compression in all cylinders. The trouble is the fourth one is sparking good and the fresh fuel is squirting nicely out of all injectors, but it turns over slowly (with compression from 35 to 165, most of them on the low side). My question is what can I pour into each cylinder while the piston is near tdc and the engine is tipped with plugs straight up to dissolve the castor oil that has the rings stuck? I'm considering a shot of methanol alcohol and give it a day or so to work before removing it and moving to the next cyl. Any other advice?

[LakeFever]

Heat helps soften it up. Methanol will work but it takes time. Maybe 24hrs soak type thing so you would have to do one cyl at a time. You could always pop the heads, then use brake clean or whatever solvent and wd/40 before buttoning back up.

[aj06bolt12r]

Diesel fuel would probably work well.

[laser_ED]

Go to your local auto store and get seafoam spray,,load each cyl up let sit overnight,,,,or go get mercury engine tune and do the same thing.Castor oil also clogs up your vacum port on EFI engs,,,horn ,svs,or laser inj are all prone to clogged vacum ports....

[d&smach]

Go to your local auto store and get seafoam spray,,load each cyl up let sit overnight,,,,or go get mercury engine tune and do the same thing.Castor oil also clogs up your vacum port on EFI engs,,,horn ,svs,or laser inj are all prone to clogged vacum ports....

The only thing I found online for removing old, dried castor oil was from the R/C folks. They all said to use model fuel (methanol/castor oil ) and heat it up in a crockpot to 150 degrees! Does anybody have a crockpot I could borrow to submerge an entire 2.5 in?! Actually I already tipped the engine up and put the piston at the top on the worst low compression cylinder, filled it with mostly methanol with a bit of castor oil just because, filled it to the spark plug threads and watched. I was surprised how fast the mix drained past the rings to the tdc piston, maybe ten minutes. I the filled it with WD40 and it took a lot longer to drain. I plan on leaving the two 165 psi cylinders alone. I'll do a compression check on the first one I did that was only 35 psi and see if I made any progress. Once it is started and allowed to run and warm up it was amazing how the compression came back to almost identical numbers on the other three engines.

[LakeFever]

Pop a spark plug, piston to tdc, point a heat gun with a tapered nozzle in the hole for a couple hours. Then pour in the meth and start cycling it. Should free it up

[d&smach]

Pop a spark plug, piston to tdc, point a heat gun with a tapered nozzle in the hole for a couple hours. Then pour in the meth and start cycling it. Should free it up

I didn't think of that, it seems heat really plays the major role in ridding the old castor. I'll give it a try today, thanks!

[rjdubiel]

could pull heads and exhaust divider plat and start going at it with a torch! Also this way you can go in through the exhaust port and actually get some spray on the actual rings and land on the piston. But with heads off you can really wiggle the pistons easier. 60.00 for a set of gaskets once its done and ready to rock.

[d&smach]

After about a half hour of 90% methanol 10% castor oil mix followed by WD40 which drained past the piston/rings much slower I did a follow up compression check. Before treatment 35 psi max, after the two cleaners it was 158. I'm pretty sure after starting and running til warm up, about ten minutes, this engine will be like the others, a bit higher yet and very even compression in all. Before treatment I wasn't able to rotate the engine with a 3/4" drive breaker bar. I had to weld a short piece of drive shaft to a six foot steel bar and have two strong men hold the engine, so if it ever happens to you, it's not hopeless! BTW, it wasn't actually frozen stuck, it didn't snap loose, it just smoothly started turning with a LOT of force. We had fears that the bearings or rings were rusted/corroded together and frozen in place, but it looks like no damage was done by this error.

[mach351]

The real question here is I need to see pics of what you have quad 2.5’s on!

[d&smach]

The real question here is I need to see pics of what you have quad 2.5’s on!

Go to "general boating discussions" and look at "Lightest drag hydro?", I just posted it, with pics.

[OnPad]

Sounds like you got it sorted.

Just thought I would second a couple posts above for diesel or seafoam, working great for stuck rings.

Also, I have a few models that run nitro/methanol. The engines tend to rust, unless you put after run oil in em before storage.

[d&smach]

Just when my hopes were high and everything was going great and every cylinder I treated came back from around 50 psi to over 150 psi this happened. I had only one cyl to go, 56 psi, I used the alcohol until it all drained past the rings followed by wd40. After about a half hour I noticed the cyl was completly drained and I gave it a good spin with plug out followed by a compression gauge, it went from 56 psi to 25 psi. I'm not quite sure whats happening here but I have a feeling it won't have a happy ending. With five good cyl and one that is 25, do I dare start it up, warm it up and see what plays out? What possibly could have happened?

[wolfgangb]

Just when my hopes were high and everything was going great and every cylinder I treated came back from around 50 psi to over 150 psi this happened. I had only one cyl to go, 56 psi, I used the alcohol until it all drained past the rings followed by wd40. After about a half hour I noticed the cyl was completly drained and I gave it a good spin with plug out followed by a compression gauge, it went from 56 psi to 25 psi. I'm not quite sure whats happening here but I have a feeling it won't have a happy ending. With five good cyl and one that is 25, do I dare start it up, warm it up and see what plays out? What possibly could have happened?
Snagged a ring?
rgds, Wolfgang

[LakeFever]

I’ve gambled enough over the years to risk that plus the back of mind tingles drive me nuts. I would pop the head off. Its a quick job and a cheap gasket. Promarine for parts is who most of us use. Its best to be sure than to wonder

[d&smach]

If I were to start it now after it lost so much compression in only one cyl from solvents and lubes, (58 psi down to 25 ) I'm assuming instead of a miraculous fix, I could do damage to the cyl / piston? Wouldn't pulling the head and only being able to just see the cyl wall and piston top still give limited info about the cause?

[Baker343]

Pull both heads for peace of mind. It aint that big of a deal and if the cylinders are good you have more access for lube or some magic elixir.

[d&smach]

I'll take your advice, I think it would be the best route especially since I'm not in a pinch for it, it's a spare, but I still want the peace of mind knowing it is ready to go. Oddly as I accumulated the four engines I wound up with only one exhaust tuner. I have another hydro I'm putting together with a 12" mid section. What should I be looking for as far as tuners go?

[laser_ED]

What 2.5 engines are you working on?? steel bore,200,225 or nic 245,260,300.I see you are having good luck freeing up your engines ,,just wondering what you are dealing with..Since your compression is 165 you already have modified powerheads?? When you ask about tuners I think mercury knew what they were doing and would go in that direction...

[bobkatz]

Be real careful using methanol as a solvent as it has low(like none) lubricity qualities. Once the castor is gone you're basically metal to metal and could cause a snag or metal transfer. I'd be more inclined to use WD-40, kerosene, diesel fuel, premix gas, etc. JMHO Good luck!

[patchesII]

Takes very little time to pull a head and intake to pull the questionable piston out and get a look at it. If these were my engines and it took that much to get them rotated over I’d tear them down for a proper cleaning and reassembly

[d&smach]

I took the head off, cast iron cylinders and a perfect non-scored bore. It has the "o" ring type head gasket. Two of the six cylinders had 165 psi compression, then it went downhill from there to the worst being 25 psi.

[OnPad]

Not that much more work to take the intake off, and slide the piston and rods out, like said in above post.