What is best liquid to free pistons?

[startinghandle]

what is best liquid to pour down plugholes to free pistons on petrol fergy..... thanks in advance

 

[Kidds]

Diesel each day for a week is as good as anything.
Keep doing it for 5 or more days before trying to turn it. Gently rock it in third gear to turn it

 

[Jason g]

I saw on TV years ago they got some engine oil in a pan and heated it up the poured it in to free piston. Could help??

 

[averageguy54]

I use a 50/50 mix of auto trans fluid and acetone.Seems to work pretty good, especially if it has a few days to sit. A lot of fellas who repair old tractors over here swear by it. Dose it down daily, and gently try to turn it over, either by hand or rocking it in gear.

 

[Kiwi Pete]

ATF and diesel

 

[Maico490]

I saw on TV years ago they got some engine oil in a pan and heated it up the poured it in to free piston. Could help??

I remember seeing the same thing. Have also been told pouring hot water into the block after whatever oil has been soaking for a while can help

 

[Exfarmer]

Parrafin

 

[Mursal]

We drop of diesel over a few days then try a turn, see how you go ..........

 

[Landy Nick]

Freed a few seized engines from sitting for decades with diesel. Just fill the bores up and leave for a week, then drop in gear and rock the engine or try to turn over from bottom pulley or crank handle. If still seized, top bores up and leave to soak for another week.

 

[mikep]

Used to swear by Coke in the sixties, the liquid not powder. Never tried it as I hate the bloody stuff so never had any.
There was a Castrol product and I can't for the life of me remember the name but it was the chemical name not a marketing name.
It must have been withdrawn because I no longer see it but it was brilliant it could almost dissolve welds. It never failed but I lost most of it as it dissolved the tin!

 

[traineefarmer]

Brake fluid.

Failing that, blood, sweat and tears.

 

[sawdust]

Used to swear by Coke in the sixties, the liquid not powder. Never tried it as I hate the bloody stuff so never had any.
There was a Castrol product and I can't for the life of me remember the name but it was the chemical name not a marketing name.
It must have been withdrawn because I no longer see it but it was brilliant it could almost dissolve welds. It never failed but I lost most of it as it dissolved the tin!

 

[mikep]

I'm going to have to try something soon as I just pulled my series one out of the hedge and it's a little seized
The dip stick reads very overfull so water is in the sump as well. That shouldn't be a problem as there is enough oil to keep the oxygen out. I often wondered if you soak the bores for a week or so and then make adaptors for the injector/spark plug holes to take a grease nipple and slowly increase the pressure along with belting the ring gear it may work? Have to make sure it's not TDC though.

 

[MrNoo]

Compressed grease, which is effectively what it will be has a lot of force behind it and more than likely do some serious damage. I dont understand why you lot want to free them off as they'll always be a step in the bore and the rings (if not broken when you un seize the pistons) will bugger themselves on the resultant lip left in the bore. Just strip the buggers down and do the job properly!!!!

 

[Mur Huwcun]

Coke, diesel, wd40, duck oil all will free them up to get it running BUT if the bores are rusty it will only wear the rings and your compression will drop significantly eventually. I’ve never had great success with a de-seized engine afterwards but saying that it’s well worth doing to get a project running in order to test the rest of the mechanicals out before strip down.

 

[X344chap]

Tbh if its seized you need need to take the head off to check the valves anyway so you can then put diesel and heat into each cylinder and chap them with a piece of wood. IMHO When you pull the pistons of seized engines you usually find broken or seized rings.

 

[Landy Nick]

As you say the sump is full of water, depends if high enough to submerge the journals. I can't see the bottom end being all that well too.
Also there could be frost damage too.

 

[Mursal]

Just strip the buggers down and do the job properly!!!!

Agreed, but its always nice to hear it running no matter how badly before a tear down, at least you know it can / was running.

 

[dowcow]

Coke sounds like someone is taking the pee... but they aren't. A mechanic I used to know used to recommend it because he could fill a bucket with it and chuck rusty things in to soak. It sounds expensive until you compare it to a bucket of penetrating oil.

 

[TheTallGuy]

Coke sounds like someone is taking the pee... but they aren't. A mechanic I used to know used to recommend it because he could fill a bucket with it and chuck rusty things in to soak. It sounds expensive until you compare it to a bucket of penetrating oil.

It's the phosphoric acid in the coke that does the trick. You can buy it online - £15 for 5l @30% concentration.