CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Advice on freeing a seized motor

The vehicle in question is a 2006 Chinese dirtbike with a 200cc Lifan engine. (Single cyl, air-cooled, OHV.)

I got this vehicle as payment for moving a piano. Sight unseen; had been lying in a field for 3 PA winters and partially grown in.

Surprisingly, little in the way of structural rust, seems rebuildable. The engine, OTOH, is–at least–stuck.

Right now, the engine is still on the frame. I drained the old oil, overfilled the crankcase with oil, and filled the cylinder with kerosene until it came out the plug hole.

Any advice on how to proceed? I don’t want to spend beaucoup bucks on a Chinese bike, but I do have plans for this to be a “father and stepson” project this winter…I suppose I could just chicken out and procure a used Honda engine off of a XL200 at the motorcycle salvage shop.

Depends on why it’s seized. If it’s rust on the cylinder walls I’d empty out the kerosene and squirt in some PB Blaster.

I’d fill the engine with Seafoam and let sit for a week.

If the stoddared solvent and refined oil doesn’t free the engine nothing will.

Tester

1 Like

I’ve heard you can cobble together a zerk fitting for the plug hole and force the piston down with grease??

Depends on where the piston has stopped. If it’s at bottom dead center it would have nowhere to go. Even at TDC it wouldn’t work.

Good point, my 2 cents.
As a matter of fact, steam locomotives had “locked” axles with the pistons offset specifically to prevent the opposing wheels from stopping in a position where neither would be able to turn the axle to start the train. Were they both to stop at one or the other end of the piston travel, and they inevitably would, neither would be able to turn the crank. Exactly the same principle applies here. If the piston were at the end of its travel (either end), pressurizing the cylinder through the sparkplug hole would be unable to turn the crank and break the piston free.

Proceed slowly and work it back and forth,sometimes you can find a device that screws in the sparkplug hole that will help break a piston free,but you may end up with a free piston and no compression,if that happens put some oil in the cylinder(hydraulic seal and you may get it to fire) if you get it to run a bit the compression may come up-Kevin

If anything will work…it’s PB Blaster. You might have to leave it in a couple of days to really get the benefits.

SUCCESS! Mixed in some ATF with the kerosene…after 3 days of sitting, dropping it in gear and pushing it across the basement floor turned the engine over! (And splurted kerosene all over everything…kinda smelly, says the Mrs.)

Since I have all winter, think I’ll take the engine off the frame and disassemble/rebuild as necessary.

Good news, and good luck with your winter project!

Congratulations! Now for the fun parts, the project.
You’ll be speaking Chinese in no time… Do they use metric or SAE??

Ride with care. Two hundred CCs is plenty enough to get you in trouble out in the dirt and I say that from past experience which is likely going to lead to a future experience with another knee surgery at some point; and I was only working with 175 CCs…

Cool! Post a picture, I never saw this type of MC. I’m in PA also, last Winter was a bugger. I’m in the Poconos, whereabouts are you Joe? Rocketman

Is there a parts source for those bikes? I have seen a few for sale at near scrap metal prices but never considered them worth looking at due to lack of parts. A few years ago the Chinese built Honda clones were marketed heavily in this area and they looked impressive then but when the shine is knocked off and the owner gets a case of road rash they let them go cheap.

Well Im too late but I was going to suggest trying apple cider vinegar. Sounds weak but it really does eat rust when soaked for days in it.

The trick with the grease fitting does work. I made one up with an old sparkplug and used it to free up a stuck Yamaha 750 that was in a saltwater flood. The piston does have to be somewhere above BDC and both valves need to be closed but it does work perfectly. I had previously tried every other solvent out there such as PB Blaster, Sea Foam and a few others to no avail.

“Is there a parts source for those bikes?”

One would think so. I know a guy who sells them at a large flea market in a nearby town and sells new ones dirt cheap. They have a bad reputation for not running too long but people still buy them. One of the reasons is that they actually look great but, as we all know, looks ain’t everything. If he ever gets in a Cushman Super Eagle clone…I’m going to buy one. I’ll adapt a Briggs & Stratton engine to it to keep it on the road…if I have to.

I heard that deep creep seafoam is best for this? I need advice on if I’m going to get anywhere I’m freezing up the engine if it’s the winter time and 30 degrees Fahrenheit outside??? Any advice?

I’ve generally filled the cylinders with ATF on old, seized up engines that I’ve ressurected. After letting it sit for up to a week, I crank it by hand using a breaker bar with the plugs out.

1 Like

Yes… this post is about a SEIZED engine not a FROZEN engine because of temperature. In other words, one that is locked up because of broken or rusty parts, not one that is cold.

Cars are designed to run in -40 F as well as -40C. 30 degrees is nothing to a properly maintained auto. You don’t need to add anything to the oil or the gas.