Hello all, I have not been on the forum for a while and I hope all my pals on here are doing well.

My '98 EX has been running nicely since I did the timing belt/water pump a few months back. The car leaked oil like crazy due to the oil pan after a new pan gasket and Honda bond now it is all 100% dry under the car and zero leaks. However for the first time since owning the car I have noticed that it has been using oil (about a quart every 4-500 miles) it still runs great and no smoke to speak of.

I have a compression tester somewhere that I will dig out on my day off. The PO installed a y7 block (the milage on the block are unknown to me) under the factory y8 head which has 130k on it. Is there any hope of it being valve stem seals? I pulled my plugs and they look decent but maybe a tad on the lean side. Is there a possibility of a head gasket failure without other symptoms? No bubbles in rad tank or fuel in the oil.

Now another issue I have is poor milage recently as well as codes p0430 and 0420 both indicating the cat has died. I have not replaced the rear o2 sensor but the upstream one is new denso. I checked the price on a new cat from Honda and it's 500$ or more. For my 1500$ car that pricey catalytic converter is out of the question, is there any generic brand that may work for me?

I suspect the oil consumption is an old issue that I just noticed after solving the oil pan leak. I also am afraid that if I replace the cat then it will be destroyed by the burning of oil, however strangely enough the plugs do not indicate that the oil is burning. Any pointers about these issues are appreciated

as I am not too familiar with these engines but I am getting better!

 

magnaflow is probably the only one I see worth a dime atm.

You might have other oil leaks that need to be looked at or your rings are gone.

 

Wet versus dry compression numbers should answer question about worn rings.

Any blue smoke in the exhaust? Burning a lot of oil will kill a cat pretty quickly. Don't replace cat until you solve the oil loss issue.

Occasionally, an exhaust leak downstream of the primary O2 sensor and upstream of the secondary O2 sensor will throw P0420. Worth a look.

 

Tony_2018 there are no other leaks under the car at all. muellersfan thanks for the tip on a possible exhaust leak downstream of the cat! I didn't know a leak back there could impact the O2 readings. Also as far as I can tell there is no smoke leaving the exhaust pipe.

I dug out my compression test kit and will post my wet/dry compression results this evening. Thanks again!

 

An exhaust system leak will suck outside oxygen-containing air into the exhaust. This confounds O2 sensor readings.

Sometimes little oil from a large oil leak accumulates on the engine exterior, so also look for subtle signs of an oil leak.

 

Yup, which is why a leaking exhaust is always bad

 

Okay, I believe it failed the compression test for sure. All cylinders read 95-98 psi when dry. When wet they would read around 102-105. It looks like it's time for a rebuild or a new short block.

These readings were taken on an OEM brand compression gauge with the engine at full operating temperature and throttle wide open.

 

Approximately how much motor oil did you squirt into each cylinder?

During the compression tests, did you also disable the fuel injectors and crank for about 30 seconds?

 

I put about a teaspoon or slightly less into each cylinder. The fuel injectors were not disabled and the pedal was at WOT I cranked until the gauge would go no higher.

 

Repeat the tests with the fuel injectors disabled. This is easily done by disconnecting the distributor connector(s) or removing the 15A hood ECU/PGMFI fuse.

 

Okay will do and I'll report back shortly

 

Okay now cylinders 1,2 and 4 are showing 120 while cylinder 3 stayed around 98 psi dry. The oil increased pressure around 10psi on cylinders 1,2 and 4 but only around 5 psi on cylinder 3. Still not as high of compression as I would like to see

 

Also the compression is building fairly quickly, on the first engine rotation of the engine the gauge jumped to 70psi but after 100psi it took more rotation to build pressure

 

You have one bad cylinder. Do a leakdown test on cylinder 3 to determine where it is losing compression. You may have a leaking valve or severe ring issue.

You also may want to clean the engine exterior to identify potential sites for other oil leaks.

 

Well at least we have got it narrowed down, and by leaking valve could that be the valve stem seals causing the compression leak? Or is it the actual valve itself leaking by?

I will do a leak down test as soon as I can. Unfortunately this is my daily driver so I have to test and repair based on my work schedule.

And since only number 3 is showing lower compression and none of the others can I safely assume the head gasket is still okay?

Thank you for all of your help and the information you have given.

 

A bad valve seal would no affect compression but would cause loss of oil and oil burning in a cylinder.

Not yet.

My pleasure.

 

Thank you very much. I am going to conduct a leak down test and probably do the valve seals just for kicks this week sometime. Like you said once the oil consumption is solved then I'll go after the catalytic converter.

​I will update as I go!

 

Also one last thing I am curious if the valves can be misadjusted enough to cause an issue like that? The car does have noisy lifters at idle and I have not done a valve adjustment since buying it

 

A valve adjustment is worthwhile, but more likely is a burnt exhaust valve and/or worn rings.

 

valve seats could be out of spec and not seating properly, burnt valve, worn rings. Leak down

 

Well today I checked my oil before work and it was low on coolant about 16oz worth low on the overfoverflow. This is the first time my car has ever ever needed any coolant added.

Beginning to look a lot like that head gasket I think. Any other possible suggestions before I rip the head off tomorrow?!? Thanks everyone!

By the way I have been unable to access compressed air for a while so the leak down test was not possible.

 

The head gasket is one of many engine sites where coolant can be lost.

 

I also noticed some aluminum flakes in the radiator with the cap off. And there are some bubbles with the car warm and under acceleration

The water pump is aisin and is brand new so I don't suspect the shavings are from the impeller or it's bearing.