Questions tagged [piston]

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Piston leaked 1 cup of alcohol in 1 hr

I am analyzing a cylinder leakdown across all 6 cylinders of about 90% in each cylinder. After repeatedly confirming it wasn't the valves or the head gasket, I removed one of the heads and poured 1 ...
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2 votes
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116 views

Likelihood of every piston ring corroding the same rate

I performed a rebuild of my both cylinder heads on a V6 engine, in order to grind leaky valves. I performed a test of each valve pouring isopropyl alcohol in the intake/exhaust chamber and waiting ...
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Testing piston rings by pouring isopropyl alcohol in cylinder chambers with heads off

I took cylinder heads off for some maintenance, grinding valves among others to improve compression. I tested the valve seals by pouring isopropyl alcohol in intake and exhaust cavities and waiting 12-...
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1 vote
1 answer
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How much should you clean dirty pistons and valves when you aren't removing them?

I took the heads off so I could get some broken exhaust manifold studs out and retap (actually I was advised to use a Heli-Coil instead so doing that) one of the other stud holes. The piston heads and ...
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-1 votes
3 answers
55 views

Can pistons ever be extracted from underneath?

This is a very high level, conceptual question: it seems to me like every engine is designed so that pistons are extracted from the top, which requires removing cylinder heads, a huuuge pain in the ...
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1 vote
1 answer
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Testing piston ring

One of my cylinders is leaking and I have determined so far that at least one or both of the intake valves are leaking. However, now that I have that cylinder head off, I would also like to test the ...
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1 vote
1 answer
38 views

Grinding/rattling Noise from engine accelerating on both idling and driving Suzuki G10 3-cyl Engine

I am facing an issue of a rattling/grinding noise from engine left/lower side particularly in warm engine. Car is Suzuki cultus with 3-cylinder non-efi G10 engine and running on petrol. Inside cabin ...
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3 votes
1 answer
92 views

Can one detect coolant leak due to blown head gasked by visual inspection of pistons/spark plugs?

I have problems with my 2004 Honda Civic. My engine overheats and there is no hot air coming to the cabin, even if the temperature gauge shows Hot. Every mechanic I know told me that it is a clear ...
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2 answers
70 views

If you can manually push in a brake caliper piston with a screw tool, can it still be bad?

I had noticed a burning smell in my right rear brake, suspected caliper issues, and I decided to do a brake job (2009 Mercury Milan). After thwacking off the tightened caliper with a hammer and ...
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0 votes
1 answer
50 views

OS MAX FS 70 Exhaust Thread Size

I was trying to figure out what kind of thread size the OS MAX FS 70 engine uses for its exhaust connector port. I am talking about the following (green circle) I could not find this in the manual, ...
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1 vote
1 answer
93 views

Piston too tight?

I am rebuilding a previously seized engine and after sanding the sidewalls of the cylinder and piston with 1500 grit sandpaper (there was absolutely no other choice) The piston requires much force to ...
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0 votes
1 answer
384 views

Finding TDC with a screwdriver.. what if screwdriver gets stuck?

I was performing a leak down test on a chevy vortec 4.3L V6. In order to find TDC on the #3 cylinder, I stuck a screwdriver down the spark plug hole and slowly turned the crank pulley with a wrench. ...
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1 answer
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What effect would a hole out of the bore at the bottom be?

My end cap bolt dislodged from the piston and ended up in the sump, it broke right through the bore at the bottom making a small hole about 0.5cm^2. I was intent on replacing the piston and bearing ...
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1 vote
5 answers
6k views

Do you have to machine the crankshaft after a spun main bearing?

I had a spun main bearing due to low oil, the crankshaft journal is pretty scratched, no dents just looks spun on the surface. To the inexperienced diyer it's hard to imagine this would be a huge ...
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I have a 2008 Ford Expedition XLT

I have a 2008 Ford Expedition XLT. While changing my spark plugs I didn’t push them down as far as was required therefore on two of them the hook broke off and now it’s making a clacking metal sound. ...
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1 vote
1 answer
95 views

How does enough oil remain after combustion to lubricate during exhaust stroke

To my understanding, cylinder walls are lubricated by retaining a tiny amount of oil in the honed or otherwise manufacturing prepared cavities in the cylinder walls, so that when the piston rings ...
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1 vote
0 answers
149 views

What is the plastic plug for on the bottom of an SU HS4 Carburettor Piston?

Please could somebody explain the purpose of this plastic plug on the bottom of my SU HS4 carburettor piston? The lip of the plug protrudes very slightly from the bottom of the piston (shown bottom ...
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0 votes
1 answer
180 views

Can missing two oil changes cause piston rings to crack?

Car is 4 cylinder Astra. !.4 engine no turbo charge. Last service 8500kms. Missed 2 services, rings in number two piston failed at 44000kms. Oil level always maintained. Car only driven on sealed ...
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3 votes
1 answer
209 views

1986 El Camino: deprecation

I have a question about my 1986 el Camino, as relates to how much it has or hasn’t been damaged after a 6 month hiatus from action. Last July I bought a 1986 el Camino from a private seller. The ...
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2 votes
0 answers
64 views

Does a 2-stroke engine needs "break-in" after replacing cylinder and piston?

I just replaced cylinder and piston (with new gasket, rings, etc) in a 2-stroke 52cc string trimmer engine. It started at the first pull and sounds great, I let it run for 5 minutes, adjusted the carb ...
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1 vote
1 answer
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Fourth piston isn't sparking so car is losing power

What are the possible reasons that my fourth piston is not sparking. I am pretty sure the spark plug is broken but I am not sure. The car is a 2006 Scion XB. Thank you.
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0 votes
1 answer
120 views

Bought a damaged used 2SZ‑FE engine in Sweden. How to check if piston ring is damaged without using a borescope?

Despite using https://en.bildelsbasen.se things weren’t Utan anmärkning as described. We found some engine parts filled with water (which by the way means the generator no longer works so we took ...
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2 votes
0 answers
457 views

Bent push rod, valve bent as well?

so i finally got around to opening up the head of my lawn mower and found out why it wasnt running. the intake push rod is bent. and the exhaust is straight. obviously my valves were way out of spec ...
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2 votes
2 answers
92 views

How to clean up carbon

I was wondering what the best way to clean up carbon off of the Pistons and valves is since I have to change 2 head gaskets I heard abrasive cloths and cleaners aren't so good for the piston heads, ...
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0 answers
90 views

Does this piston look normal?

I noticed a slightly reddish color on my pistons. Is it normal? It's an '08 Mercedes-Benz E350, gasoline (petrol), with 35k miles. Here is a little color correction:
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1 vote
3 answers
5k views

Is it possible to repair a piston in an engine

Continuing from my previous question (here) one of the pistons have no combustion and so the car is only working with three pistons, and there is a sound like a piece of metal smacking against ...
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1 vote
2 answers
1k views

How are compression rings lubricated?

My question relates to the lubrication of cylinder walls and piston rings. It is my understanding that pistons in cars consists of 3 rings; two compression rings and the oil/scraper ring. As far as I'...
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0 votes
1 answer
132 views

Removing Cylinders from engine block

Trying to take apart my bmw n51 motor for fun and not trying to rebuild it becuase it toast. Took evetthing atchatchet to block off and finaly got the cylinder head off. The big end bearing is exposed ...
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1 vote
2 answers
449 views

Lancer 2004 Piston Slap Concern

So yesterday i figured out my car has a piston slap because it keeps ticking during a cold start and goes away after warming up. Car is a lancer 2004 and has 260k KMs. I changed the engine oil to 20w-...
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1 answer
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Compression test

I have a 2002 Toyota Corolla (1zz-fe engine with 236k miles on it) and did a compression test on a warm engine. My readings are: 150 - 150 - 140 - 175 I've read that the difference should not be ...
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3 votes
2 answers
777 views

piston damage impact

something got in and caused these scratches. can/will they cause blowby if reused? I figure if the placement of its .018 mil piston ring gaps matter, then the gaps from these scratch just may as well....
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2 votes
1 answer
754 views

Can the bottom of a piston be scratched and not damage the cylinder?

I went to a mechanic and he showed me this custom piston made out of molten car pistons (there was no other option in this case). My question is: Is the scratch from the side of the piston going to ...
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2 votes
0 answers
883 views

Modify (cut) piston skirts: does it also cuts its lifespan?

I'm temped, as a challenge to a problem that raised when getting ready to assemble my engine, to modify the pistons skirts since one of the pistons got a crack in the skirt, under the pin side. I see ...
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4 votes
1 answer
65 views

Pistons ordeal: more pistons problems; two issues in one question

So, still having problems rebuilding this old engine (Skoda Estelle 120, 70's, RWD, rear mounted engine). First of all: getting new parts is out of the question since I have no access to those. So I ...
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2 votes
1 answer
1k views

Piston deck clearance: is 1.4 mm under deck too much?

I'm installing a piston set in a Skoda Estelle 120 engine. I know this is not a definite way to measure piston to deck clearance, but it jumped to my mind to measure it with a vernier caliper using ...
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5 votes
2 answers
4k views

Rebuilding an engine: pistons installed, crank rotation "very" stiff

As I'm assembling my engine back (Skoda Estelle 120, 70s, RWD, rear mounted engine) I have the following issue: installed crankshaft, camshaft and distribution chain, torqued as manual recommends, it ...
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9 votes
3 answers
4k views

3 rings vs 4 rings pistons: which design is better?

The engine I'm rebuilding (Skoda Estelle/120, 70's, RWD, rear mounted engine) was manufactured with two different pistons, depending the fabrication years: one piston kind has 4 rings and a cut from ...
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4 votes
1 answer
4k views

Rebuilt engine started, but with strong clanking sounds

So this is another question about my Skoda Estelle engine rebuild project. Now it cranked and started, after a session of neither of those. To fix that problem I released the head bolts and retorqued ...
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6 votes
1 answer
2k views

Do my new oil rings have an excessive gap?

Today I measured the new piston rings I will use while rebuilding my old Skoda Estelle engine. Skoda Set They are new from the Skoda factory (or that's what the box says), but they were ...
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5 votes
3 answers
291 views

Extracting piston rod's "wire" C clips

So now that I'm getting ready (soon :) ) to fit new pistons in my old Skoda Estelle engine, I found that the piston rods have "wire" C clips. I mean, they look like a piece of wire, no "eyes" or tabs ...
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3 votes
2 answers
2k views

Rear brake piston hard to turn back in, uneven wear on pads

2010 Toyota Matrix, Manual, Base model 1.8 L Some context It was time to replace the rear brakes (noise, grinding). When I took everything apart, I found that the inner pads were extremely worn, at ...
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3 votes
1 answer
282 views

Is it really necessary to resurface cylinder and substitute piston?

I believe this is common in motorcycle maintenance, I have heard in some places that, once you get the piston outside the cylinder there is no way back, you need to resurface the cylinder and get a ...
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10 votes
2 answers
6k views

What's gonna happen if I disconnect 'single piston'

I saw similar topics but that did not explain my things... As we can see 4 stroke engine with 4 pistons Is there any chance (only for test) to 'switch-off' two pistons? For this example I'm talking ...
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7 votes
2 answers
4k views

Where does the piston stop after the ignition is turned off?

Compression stroke at TDC or Exhaust at TDC or somewhere else? Is this position fixed or does it depend on other conditions?
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7 votes
2 answers
671 views

Safe to buy new piston for your two wheeler engine

I own a Honda Stunner 125 CC motorcycle. I bought it in 2009. Since last year I have observed that it is emitting white smoke. Mechanic recommends that I purchase new pistons or after some time ...
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2 votes
2 answers
1k views

Should I remove the rings when cleaning a piston?

I want to clean my piston in a small ultrasonic cleaner (with distilled water). Do I need to remove the piston rings to do so, or can I leave them on and make sure it dries completely? If I replace ...
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5 votes
2 answers
2k views

Cleaning pistons and cylinders with oven cleaner

Can I use oven cleaner (composition: 5-15% aliphatic compounds, 2-aminoethanol, butane and propane...) to clean the carbon off the cylinders and pistons of my BMW R80GS 1991 Motorbike (without ...
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  • 358
5 votes
2 answers
317 views

Pivoted curved-path piston engine

Years ago, I saw a documentary about engine efficiency where people were testing a pivoted, curved-path piston engine. The claim is that the standard piston engine, with straight up-and-down path, ...
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2 votes
1 answer
6k views

How much force is needed to push a piston down? [closed]

Combustion from fuel and air is used to push a piston down. When they combustion it creates a lot of force, my question is how much force is needed to push the piston all the way down when the vehicle ...
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14 votes
4 answers
8k views

Do pistons keep moving when the car stops?

When you are driving and stop at a light, do the pistons still move up and down due to combustion? If not how will the engine know when to combust the fuel to keep it moving?
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