Engine lost compression?

Good afternoon,

The first thing I would do is a compression test to verify if you have an internal engine issue.

https://www.2carpros.com/articles/how-to-test-engine-compression

and

https://www.2carpros.com/articles/the-reasons-for-low-compression

Start there.

Roy

Hi Roy, I have done a compression test. 4 Cylinders is at 145 psi (mainly the back and third in front) first cylinder has 0 psi 2nd has 20 psi.

Okay, then the head has to come off to find the failure.

That will be a lot. With 230,000 it will be difficult to say if it is worth fixing. I would figure at least $1,000.00 to start.

Roy

Thank you Roy, very helpful.

You are welcome.

Always glad to help.

Roy

2001 Honda Accord mileage: 98,500. My Accord started running bad, I did a leak down test on it to find no compression in the #1 cylinder. I've taken the head off to find a burnt exhaust valve. Should I have the head sent out to have it magnifluxed or am I ok to go back together just lapping the valve in. The head looks good, no other burnt valves, really clean. One more thing, they say the price on the head gasket is $80. This seems awful high to me. I appreciate your time in this matter.

In your situation, we would grind all the valves and valve seats. Check the valve guides for wear and replace all the valve stem seals and the head resurfaced. If your engine has been overheated or if you are concerned, have the head checked for cracks.

I have a 2000 Honda Accord w/a VTEC 4 cylinder engine that has poor compression in one of the cylinders. The "bad" cylinder has only 60 lbs of pressure where as the other 3 cylinders have 175-200 approx. We have not gone any further into the cylinder diagnosis yet - what would you say I might be looking for?

[quote:c6dfe52284="ndavis"]I have a 2000 Honda Accord w/a VTEC 4 cylinder engine that has poor compression in one of the cylinders. The "bad" cylinder has only 60 lbs of pressure where as the other 3 cylinders have 175-200 approx. We have not gone any further into the cylinder diagnosis yet - what would you say I might be looking for?[/quote:c6dfe52284]

Did you do both wet and dry test? also confirm it with a leakdown test.

We had only done the dry test, next we were going to do a leakdown test.
typical causes? - what would you say I might be looking for?

Check valve clearance! Failure to piston rings in Honda is not very common, unless you overheated engine.
This is important, if the vavle cearance goes under lower tolerance, it starts to burn valve, and progress can be quick.
If this is the case adjust this particular valve with +0.05 mm over max tolerance value. For example if the clearance is 0.25 +/- 0.05 mm adjust to 0.035 mm. Run car for 500 to 1000 miles, check valve gap and compression again. If compression is back to aceptable value, you are lucky.

I have a 2000 Honda Accord Sedan 350,000 miles. I recently go a compression test showed which showed 120, 90, 70 and 60 pounds of pressure in each of the cylinders. Do you have an idea about what the compression test means about the engine?

That refers to how hard each piston is squeezing the air it sucks in. Even 120 pounds is low. The rest are real low. That can be expected with such high mileage. Piston rings seal the air in and prevent it from leaking out into the lower part of the engine where the oil is. Those rings normally wear with age. There's also valves that let the air in and the exhaust out. Over time they too will not seal as well as when they were new.

A compression test is just a fast way of determining the quality of each cylinder and its ability to make power equal to all the other cylinders. Your mechanic can also do a more involved "cylinder leakage" test, or "cylinder leak down" test. That will identify exactly what is responsible for the low compression. They will likely elect to not do that test with the mileage you listed because everything is going to be worn. No professional will do a valve job, for example, and leave all the other worn parts in the engine. This is likely a case where the engine served you well but it's time for a total rebuild.

So I basically need a new engine?

It has 350,000 miles. It doesn't owe you anything.

You haven't described any problem or symptom so it's impossible to know what the best remedy is. You also have to look at how the compression test was done and if correct procedure was followed. The same conditions must be present for each cylinder's test. Looking at the numbers you listed, with each one getting lower in order, you'd have to suspect the procedure might be at fault. First of all, a battery charger should be attached to the battery and set to a slow charge rate. The compression test requires cranking the engine at least five revolutions and doing so runs the battery down. By the time you get to the last cylinder, it's going to be cranking slower which will make the readings lower.

During cranking, oil gets scraped off the cylinder walls. That oil helps the piston rings seal and do their job. It gets sprayed onto the cylinder walls when the engine is running at normal speed. When cranking the engine, it's running too slowly to spray oil so by the time you get to the last cylinder, it's going to read lower than normal. Experienced mechanics will check for that by repeating the test on the first cylinder after all four have been done. If it reads a lot lower than the first time it was tested, the procedure is more to blame than the engine wear.

The engine must also be warmed up before starting the compression test. If the mechanic gets interrupted in the middle of the test and the engine has time to cool down, parts contract and don't fit properly. The piston rings won't seal as well as normal.

On initially turning over the engine compression is observed for two strokes with a backfire resulting. The engine then rotates freely with no compression. I initially thought it was the starter motor. The starter motor is okay. On doing a compression test as I said above , no compression was detected in any cylinder. Checking the timing belt all is okay with timing markers aligned. There is a strong spark across all spark plugs. The fuel pump was defective and was replaced . initially started the car re-positioned it about 20m away and then turned it off. It was working perfectly. However since then it refuses to start. All fuses have been checked.

I am a little confused with some of the info that you provided only because some of it is not related to the compression of the engine. Let's start with this guide that explains what and why you need compression:

https://www.2carpros.com/articles/what-is-engine-compression

Then we need to move onto finding out why you have no compression. So when you say you have no compression, what was the actual PSI reading on the gauge? Was it 0 PSI on each cylinder? If so, I would think we have a hole in the block or the head is not sealing.

Can you get a recording of what the engine sounds like when you are cranking it over? Thanks

Engine Mechanical problem
1997 Honda Accord 6 cyl Front Wheel Drive Automatic

why is there no compression on 4 of the 6 cylinders on this 2.7 accord...i pulled the head off in the front and no valves are bent..i just changed the timing belt and didnt start...#1 and #4 have 140 and 120psi..the rest have o psi !!

You need to verify the valve timing

i lined up the marks on the gears but it still wont fire and the compression was as i explained...what can be 180 degrees out? the cam or crank?

You probably on the exhaust stroke when you line the cam and crank

Do this lift the distributor, hold rotor in place and have it postion to no.5 cap tower then fully install the distributor and see what happens

so the crank may be 180 degrees off?and the cams can only go one way?

Was driving great then going to work one morning just shut off. I did compression check,#1 90#230#3 30#4 90. could that be head gasket or timing slipped? Or cam? I am stumped. Please any suggestions?

Do a wet compression test, that is add a small amount of oil into the cylinder before testing the compression. this will seal the bottom end and if the compression comes up the problem is ring related. if not valve problem do this first.

Car sat for 6 years. Checked filter system, oil and other fluids good, removed spark plugs and poured a capfull of oil in to each cylinder, cranked over, poured in oil again and cranked over, re installed spark plugs, pulled gas fill hose and sucked fuel from fuel tank, added 5 gal. of 93 octane, installed battery. Using carb cleaner i sprayed small amounts at a time into the breather hose past the air filter 10x and the engine began to run on its own. Warmed engine to full operating temp then reved engine a few times. Drove the care 10 miles and had no issues. Drove the car today 50 miles with no issues. Cranked engine at least 20x today. Engine cooled for 3 hours... proceeded to crank the engine and found ZERO compression on ALL cylinders. Looked inside of valve cover to find the valve train operating normal, all pulleys turning normal... What happened? TY!

Hi CycleDr.II, Welcome to 2carpros and TY for the donation

Verify the valve timing if its correct, T/belt could have slipped a notch or 2-check it by also doing a cylinder leakage test.

Hi there,

Thank you for the donation,

You can do one of two tests here easiest is a wet & dry comp test, add a small amount of oil to the cyl and do a comp test, the oil will seal the ring-lands and if comps come up the problem will be rings if no valves, a leak down test will be more precise, an adaptor screwed into the plug hole and low pressure air added with the piston at TDC, you can then listen fir air leaking in the inlet, exhaust, and rocker cover (ring blow by)

mark (mhpautos)

A tooth on the belt would not cause this... will it?
I had already did the wet (oil) test... knowing it wouldnot help but did it any ways last night...
The pistons are moving but I tell ya...

There is 0 psi compression on ALL 4 cylinders ALL at once... ? All I did was turn the engine off and then 3 hours later tried to crank... please help...

TY guys and I wish you a Grand weekend!

Final test is do a leakdown test-if its leaking pressure it should come out of the tail pipe if its exhaust valves, intake valves would be out from the throttle body, rings will be out of the oil dipstick-You have a nice weekend too.

How do I free up sticky valves?...

You can use the old timers trick-use a qt of ATF and run the engine or use seafoam or the marvel mystery oil if none of them work its time to break it open

Engine Cooling problem
1992 Honda Accord 4 cyl Front Wheel Drive Automatic

How can you tell if you have a warped head with a compression tester if the car won't start up to warm it first?

The compression will be lower than all the other cylinders. However, this could be anything else.

You will need a leak-tester to determine exactly where the leak is.

i broke a timeing belt on a 1996 accord 2.2 singe cam.ireplaced it,now i have no on compression in #2,an #4 cylinders.i removed head and found no bent valves.what next.

Did you do a dry and wet test-Might want to do a leakdown test to find out where its leaking at.

Did you inspect and mike the camshaft lobes?

sounds like a camshaft problem. is it turning?