302LVR

Hello to all i'm new to this forum and decided to join since its very helpful. I'm a pretty good DIYer and i'm mechanically inclined but its the first time i do a head gasket job on a prelude with an h22a4. I recently fixed a blown head gasket on this vehicle and assembled everything back succesfully using ARP head studs, Fel-Pro MLS head gasket, as well as a having the head milled down .005", new valve seals, new valve seats, etc. The car starts up fine, idles and runs smooth with no missing but once i drive it and try to engage vtec is where things are getting weird. Once i'm at normal operating temps I noticed that the car will engage vtec slightly but hit the fuel cut early n the car will lose power so i let off the gas n it will idle down to normal again. Usually after the vtec fails to engage fully the "OIL PRESSURE LIGHT" starts to blink around idle but usually starts going away when i accelerate the car past 1k rpm. I did scan the ECU and found only 1 code (p0135), which is an o2 sensor but i doubt thats keeping me from engaging vtec fully. I was told by other people i know that i may have a bad oil pressure sensor or even worse, a semi-clogged oil pickup tube. The funny thing is that when the car is cold n i first start it up it wont trigger the OIL PRESSURE warning light till like 15-20 minutes of the car just idling there till it reaches normal operating temp. So today i replaced the oil pressure sensor since its easier with hopes of not getting the light anymore and i'm still getting the light once the car warms up like normal. I did use regular Wal-Mart brand 5w30 oil to "clean up" the engine inside from any coolant residue it might have had when it blew the head gasket so i'm wondering if the oil is too thin since the car has 188k miles on it. After a week of starting the car n driving it around i've only put 28 miles on it so far but the oil is clean with no signs of water residue inside the valve cover or in the oil itself. I plan on changing the oil soon to a better quality high-mileage oil though. I also tested the vtec solenoid by directly applying 12v to it n its clicking so seems its working fine. What other issues do u all suggest i should check out for the oil pressure warning issue and can this be the main reason my vtec isnt engaging fully? Any help or suggestions would be greatly appreciated. Thanks. I will also drop some more info on this situation tomorrow since i seem to have other issues n worries after this job.

holmesnmanny

Check for any big dents in the oil pan, especially in the middle where the oil pickup is. It could be preventing good oil pressure.

H22Honda98

is the oil pressure sending unit functioning? i had the same problem years ago after a timing belt change. make sure the little eyelet is secured to the sensor and that it works. id change the sensor and rule that out before i went any farther trying to diagnose this problem.

also break huge posts like that into paragraphs in the future. i cant bring myself to focus hard enough to read all of that.

edit: saw you changed the sensor. reset the ecu if you havent. good practice when you change something electrical.

302LVR

Thanks. I'll try n simplify it next time i'm just trying to describe the issue with as much detail as possible. I just installed the new sensor yesterday and yes i did disconnect battery ground to reset ecu before swapping the sensor. I'll give it another shot today though. I also made sure the signal wire was secured properly. The light seems to come on once i reach normal operating temp or seem to engage vtec eventhough its not engaging fully.
When i removed the balancer to access timing belt, the front main seal looked nice n dry. Now after putting everything back together, i seem to see a little oil drip behind the cover but i'm not sure if thats coming from that seal or Cam Seal up above since i noticed oil seems to be seeping through slowly but in a very small amount. Can it be that the 5w30 oil i'm using is too thin therefore seeping easily??

302LVR

No apparent dents on the pan at all i already checked. Also this car has an h22a4 which has the aluminum oil pan which looks sturdier n i'm sure would crack if it ever got hit hard enough. It also has no apparent leaks either, i even took the extra step of installing a new oil cooler o-ring using an oem Honda one and everything is nice n dry with no leaks.

H22Honda98

I doubt the weight of the oil has anything to do with what's going on. Makes me wonder if you really do have low oil pressure and the sensor is actually doing its job. That would explain vtec half assing it and cutting out.

I've seen an improperly seated cam seal leak on first start up though and put almost a quart of oil inside the timing cover. Just dumped on the floor when the timing cover came off. So if you put in new seals consider that.

302LVR

^^^ I actually didn't install new cam seals just used the ones that were already installed by the previous owner. According to the previous owner, the car had been overheated and he sent head to machine shop to get milled for straightness and according to him, he installed new seals when the head came off(Valve cover gasket, cam seals, and spark plug seals) so nothing would leak oil. I did indeed use the non-hardening Permatex #2 around the cam seals before installing the cams to ensure a proper seal.

I also saw a video on youtube the other day where someone mentioned that a missing or worn o-ring underneath the CENTER cam cap can also cause a bad oil reading or low oil pressure for that matter. I honestly dont remember checking or seeing that o-ring when i took everything apart. I pretty much figured everything was coming back nice n fixed when i sent the head to get rebuilt that i forgot to check for that seal and who knows if the machinists lost or never re-installed that o-ring. I'm just hoping it's not enough to cause a low oil pressure reading and the vtec not engaging 100%.

I don't think my oil pump is bad as u can actually see that the valvetrain is getting oil when i start up the car n let it idle until i reach normal operating temp n then shut it off n check. I'm at a last resort here but can it be possible that the GREEN oil pressure sensor on the vtec solenoid assembly be faulty? I'm assuming this because i know thats the sensor that locks the third lobe for vtec when theres enough oil pressure and since the low oil pressure light would start blinking as soon as i tried getting vtec to engage yet vtec wouldnt engage fully and i would get that fuel cut at 6500rpm. What do u guys think?

holmesnmanny

compression test it to see if maybe the oil is going into the coolant

H22Honda98

I would take holmesnmanny's advice and do the compression test and a leak down as well if you have the means. Definitely check out every component of the vtec system and if you can, switch them out with parts that you know work from a buddy's car or something. You're going to have to narrow this down. You'll figure it out. It's always something retarded.

You either have low oil pressure or you don't. Knowing the answer to that question will help you narrow this down much faster. Do you have access to someone's oil sandwich plate and oil pressure gauge to do a quick check?

It really does sound like there isn't oil pressure. 6500 fuel cut comes in if you were to cold start the car and try and hit vtec right away and there's no pressure. Also acts very similar if you're way low on oil trying to hit vtec at operating temp.

Compression test, vtec components, then go from there.

What's your location?

snobordboy

If you have fresh oil in there, and your level is correct, I would also suggest getting a gauge on there to actually read your oil pressure. If it was just the vtec issue, I would say solenoid screen, but that wouldn't cause the light to come on.

Just curious, was the correct head gasket used for the block? If the oil was not draining from the head to the block properly due to that, or some other blockage, could cause many issues.

302LVR

I did a compression test before disassembly and after re-assembly before starting the car up. I did have lower compression in cylinder 4 compared to the rest which is making me wonder if the car is getting oil through the piston rings. Coolant is fine with no oil mixing or anything.

302LVR

I did do a compression test before and after for comparison. I do seem to have lower compression in cylinder 4 compared to the rest. I believe cyl 4 had about 125psi n the other 3 cylinders had about 185psig. I'm starting to think maybe bad piston rings on cyl 4 may be causing the low oil pressure light which would explain why it does it once the car and oil is hot at normal operating temp. I havent done a leak down test so i'll look into that as well as exchanging some of the vtec components.

I was also considering buying the gauge set to visually see how much oil pressure i have. Do you guys think i'm losing oil pressure due to the fact i have lower compression in cyl 4 possibly pointing at bad piston rings? It does start to smoke a little out the exhaust once the car is at normal operating temp when i rev the car a bit. Btw, i live down in south Florida.

302LVR

Yes it has fresh oil even though its wal-mart stuff but i purposely used it to clean out the system and do another oil change pretty soon. I added about 5.5qts 5w30 since the dipstick still marked low after pouring 5qts into the engine. I also cleaned the vtec solenoid/entire assembly and screen with gasoline when everything was apart before re-assembly. I'm looking into buying the gauge set to check the oil pressure to scratch that off the list. I also used the correct Fel-Pro MLS gasket which i test fit before install to check for proper fit and everything lined up fine without blocking any oil passages n stuff.

H22Honda98

Its hard for me to say if the low oil pressure is due to that cylinder being so low on compression,because i dont know, but its definitely something to think about. That is way past the oem level of acceptable compression differences between cylinders. how many miles are on this engine?

definitely get an oil pressure gauge on there. once you know if its low or not youll be in a much better position to diagnose this.

302LVR

188k miles on the odometer. The screwed up part is my nephew bought this car from someone who had overheated the car and supposedly got the head re-done n then he overheated it as well. My guess is that the previous mechanic re-used the stock head bolts because the car gradually started running crappier like hard to start n then one day it overheated on him. If i would've known that info beforehand i would've never probably purchased this car, but you know how teenagers are. He purchased it without asking me or anyone in the family for advice to check the car before buying.

302LVR

Hey guys just a small update. Although i couldn't do my oil pressure test yet, i was able to do a compression test today n i'm a bit optimistic that my piston rings are sealing good because i got a pretty good and even ratio on all 4 cylinders. The most i was off was about 15 psi more or less and the manual says the most acceptable difference is 28 psi. I will probably do another compression test tomorrow with a different gauge as the manual says the nominal CR is 185 psi and all my readings registered over 200 psi. I was just wondering if this difference in compression is due to the fact that the head was shaved down .005" and i also used ARP studs which ARP instructed to torque down to 90 ft/lbs compared to 72 ft/lbs with oem style bolts. This has me wondering if that's the reason why i'm registering a higher CR.

My readings for the compression test were as follows:
Cyl #1 = 240 psi
Cyl #2 = 230 psi
Cyl #3 = 225 psi
Cyl #4 = 240 psi

To make sure i was getting a good reading i performed 3 tries per cylinder, loosening the gauge n then reattaching it to make sure i wasn't getting a bad reading. I guess that's one issue to scratch off the list since i had a low CR reading on cyl #4 before which made me think i had bad rings there since the car was starting to burn oil a bit once it reached normal operating temp. Next thing i will probably check is the valve seals, although they're new, on cyl #1 since that plug had some burnt oil residue when i pulled them out n all the rest were fine. This would explain the little bit of smoke coming out the exhaust. Hopefully i can do an oil pressure test tomorrow and we'll see what happens. I'm starting to suspect i have a bad oil pump after all due to the oil pressure light coming ON and the vtec not engaging properly.

snobordboy

Compression testers vary, as long as you are within an acceptable difference cylinder to cylinder, call it good.

If you have a bad oil pump, which you quite possibly do, I would stop running the car as much as possible. Try to save those bearings, and potentially your crank and rods.

302LVR

Yup. I agree with the compression test results as well because the car idles n runs smooth almost all the time. It wasn't till like the fourth day after the initial start-up when i actually drove the car and like i stated before, the oil pressure light didn't start blinking until i tried getting into vtec and the car tried going into vtec but i felt it didn't engage fully and i lost power by 6500rpm. I have driven the car around a bit normally without beating on it for a total of 28 miles and noticed that the oil pressure light starts faintly blinking only when the car is close to idle rpm but NOT when i'm above 1k rpm. This is of course, once the car is at normal operating temp.

I will confess that i'm hearing a very slight rod knock when i rev the car a bit n thats what really worries me that i might have slightly spun a bearing already. I also consulted with another buddy that's an ASE certified mechanic and he told me its a possibility that the spun bearing might be causing the erroneous oil pressure reading since the oil isn't going thru the proper passage for lubrication. Although i still haven't done the oil pressure test with a gauge, i did remove the oil cap while the car was running and visually saw that there's oil squirting and flowing freely over the cams and valvetrain which i believe tells me the oil pump hasn't failed completely.

Worst case scenario is that i'll need to drop the crank n check main n rod bearings while i take off oil pan and replace the oil pump. It will be a bit more work but i can probably install new main n rod bearings while i take all of that apart. I'm pretty sure, and hoping that i only slightly spun a bearing but didn't bend a rod since i haven't been ragging the **** out of the car till i work out all of the bugs. I'm optimistic with this motor and would hate to have to do a full rebuild on it when it shows that it's still got good life in it. Now i have to read up on how to take apart and re-install those damn balance shafts since i know they're in the way when you remove the main caps.......Any tips or feedback from you guys would be appreciated. Thanks.

302LVR

Quick question, being that these cars are so finnicky n dependent on oil pressure for the vtec,etc., has anyone installed an aftermarket oil pressure gauge to monitor oil psi? Can the gauge possibly be mounted on the top front left side of the cylinder head where you can check for oil pressure after removing the bolt that covers that hole?

H22Honda98

Yeah of course you can install an oil pressure gauge. That's what we were taking about doing earlier so then you could get a 100% legitimate reading and see if you really have low oil pressure. If you really wanted to mount it in the engine bay I guess you could. if I were you id just put it in the interior so you could monitor it throughout the powerband and see what it does while you drive it.

I just ran mine off an oil sandwich plate. Fits right behind the oil filter.

What hole are you talking about?

302LVR

Ok i see what the sandwich plate looks like, hadn't thought about that but i'm gonna keep it in mind. An aftermarket gauge wouldn't be a bad idea anyway n yes i would install it somewhere it can be monitored while driving. The hole i was talking about is on the front side of the cylinder head, top left(when viewed from the front). I was asking cuz i had read in the FAQ section that u can read oil pressure off that port after removing the 10mm bolt that plugs up that hole. I actually bought an oil pressure gauge kit with multiple adapters from harbor freight n connected it there n got no oil pressure at idle or even when revving it up to 3k.

Tomorrow i'm gonna get under the car n remove the oil pressure switch n connect my gauge there to get a more accurate reading straight from the block. The culprit seems to be a bad oil pump but i wanna be as sure as possible it's that before i go on a mission dropping the oil pan, installing a new oil pump, n checking for spun conn rod bearings while i'm down there. Might as well change all 4 bearings while i'm down there to play it safe. The car already has 188k miles after all n i seem to hear a very slight rod knock once its at operating temp n the oil thins up.

302LVR

Finally got around to doing an oil pressure test and the end results don't convince me. I removed the pressure switch from behind the block and hooked up my gauge there. As soon as i started the car it registered close to 30psi on a cold start since the car was around 2k rpm but came down gradually. As the car warmed up and came down from 1k to about 850rpm on idle the gauge showed 10psi as the manual suggest. With the car still pretty cool i revved it up to 3k rpm and the reading was between 30-40psi but never reached 50psi as the manual suggest. Unfortunately as the car reached normal operating temp and the oil thinned up is where things went bad i guess. Letting the car idle at around 850 rpm i was only registering 4psi at the gauge and when i revved up to 3k rpm i was only getting 20psi. I guess you can definitely say i have a bad oil pump now unless.......

I recently asked a dads friend, who's an ASE certified mechanic with over 20yrs of experience about my issue n what i've done so far to try n find a solution. I told him that i've done a few compression test to double check that rings are good and he told me that i may have 1 or more bad oil control rings due to the fact that the car was overheated twice. I'm thinking he may be right since i pulled out the plugs a few days back n had 1 sp with oil residue. The smoke is very minimal when the motor is cold but once it reaches normal operating temps it smokes more. Now, do you guys think the lower oil pressure is due to a bad oil pump alone, or do you guys think im losing pressure through the oil control ring(s)? I highly doubt i'm losing oil pressure due to the rings as i'm pretty sure that the lubrication is a whole other system but regardless i just wanted to hear feedback from others who might have had this issue.

Unfortunately, i'm starting to think that even if i install a new oil pump and replace the conn rod bearings to fix the minor rod knock i have, the car will probably still smoke and consume oil a bit if i have 1 or more bad oil control rings. I can live with installing a new oil pump and conn rod bearings while i'm down there, but it would definitely suck to have to remove the head once more to pull out the pistons and install new rings n whatnot.....basically it's turned into a full engine overhaul from what appeared to be just a new head gasket job.

Needy4Speed

I saw your original post, but I didn't have the time to read the responses, only skim a few. I have a LOT of experience with the 3rd and 5th generation Preludes. First of all, the oil pressure sensors in both Preludes and other Honda's are notorious for malfunctioning. The absolute best thing to do is perform a very simple pressure test with a pressure gauge. Also, I'm quit confident that your compression issue has nothing to do with your cylinder/piston rings but rather bent valves. I first learned this the hard way by assuming the low compression of a '99 Prelude was due to worn rings which are nitrite coated and VERY unlikely to wear. Anyways, I removed the motor to rebuild it. In the process, I discovered six bent exhaust valves resulting from the timing belt skipping one tooth! Regardless, I rebuilt the engine w/ new block, high comp pistons, skunk2 cams/gears/valves/springs/seats. I also added two oil pressure gauges. Hope this helps! Good luck!

302LVR

Thanks for your input. So far my compression is good but the last test i did after installing a new oil pressure switch was indeed connecting an oil pressure gauge straight to the rear of the block. The car did show good oil pressure when cold but as the engine warmed up n the oil thinned up i was only showing 4psi @ idle and like 20-25psi @3k rpm when the manual states 10psi @idle and 50psi @3krpm. I'm pretty sure i have a bad oil pump. I haven't been able to do a leak down test as i don't have the proper equipment for that but i may need to check that indeed as i'm showing lots of blow-by when the car is running n i take off the oil cap. Funny thing is the car idles smooth but i thought the blow-by might of been caused by worn oil control rings or something as the car starts smoking more as it is warmer and the oil is thinner i guess.

I'm hoping it's not bent valves as this head was inspected and worked on before installation and the machinist told me it was good. I put new valve seals, cut valves and valve seats, and shaved off .005" since it had been overheated previously by my nephew n probably warped. Initially, the first issue i was having was the vtec not engaging fully n i was getting that fuel cut-off at 6500rpm i believe which may have been from low oil pressure. I never over-revved the car past the limiter or had any detonation i'm pretty sure which could have bent some valves. I also made sure the timing belt was on point n i doubt it skipped a tooth.....well, more like I HOPE it didn't skip a tooth whereas to i can't visually see it with plain eyesight.

We'll see what happens next but i believe i'm looking at a new oil pump and new conn rod bearings needing to be installed as i'm getting a very slight rod knock as the oil warms up n thins out on this 97' Prelude.