Engine woes

[pattejam]

Hello all,

Last night my '91 did something that really scares me and I want to get the opinions of some people on this board before I do anything.

I was driving home last night and a friend of mine was in the car next to me. When the light turned green we made a full-throttle run to 50 mph. Nothing unusual. When we stopped at the next light, I noticed my oil pressure was zero and there was a tapping coming from the engine. I got it back to my house (about a mile away) and took a look at the motor. From the front valve cover,
I could hear the tapping noise and there was a little oil smoke coming from somewhere under the motor. Also, I have noticed that in first gear, the rev limiter has been kicking in at 7000 rpm. Anyone run into this kind of problem? Thanks in advance

Cory

 

[Larry Bastanza]

Questions:

Did your oil light come on?
Did you get any engine check light? If so, codes??

7000 indicates a cold engine w/no v-tec engagement(I know that is not the problem tough. I am thinking you have a check engine light.

Fill us in.

LarryB

 

[pattejam]

Hello,

I got no indication of any problems. No engine light, no oil light. The indication was only zero oil pressure on the gauge and a loss of power.

I am religous about oil changes and actually checked oil level the previous day.

I have no engine mods except a cone intake.

Could i possibly have a vtec gasket leak as mentioned in the FAQ's?

Thanks
Cory

 

[Larry Bastanza]

It has been noted that the gauges sending units are pretty flakey, but usually under track conditions. This is why I asked about the oil light to confirm if you really have "0" oil pressure. If you start the car cold now (only for a VERY BRIEF MOMENT, IDLE ONLY) do you get oil pressure?

If you never got an oil light I am optimistic. What about your temp gauge? and idea? If the ECU thought the engine was cold it could act as you describe, sans the "tapping".

Actually I do not like the "tapping" sound you mentioned, but still early to tell.

Keep the info coming.

LarryB

 

[pattejam]

Ok, I went out and cranked it up and the gauge went from power-off zero and bumped up ever so slightly and went back down. Still no light. When it happened, I watched the gauges very closely. There was no increase in coolant temp. I will drain the oil tommorrow and look for metal or water in the oil. Thanks for your help so far.

Cory

 

[matteni]

Questions:

What does the dipstick show?

Any visible oil anywhere around the engine?

Does the coolant in the overflow tank look normal / feel normal?

Smoke behind the car when you started it?

I wouldn't start it again until you check the oil level and drain the oil and look at it.

I am guessing a little but:

You may want to inspect the spark plugs and pull them to see if there is anything obviously wrong with or below the plugs.

I would also check the PCV valve and make sure that is not the problem.

The stumper for me is oil after the 0-50 run but none later when idling? Could be oil burning through the exhaust or a leak on something hot or a greater loss of oil then you hoped. Also the pronounced ticking sound. Is it the "normal" valve sound - only louder or is it something more metallic and less rhythmic?

Hope it turns out to be something minor / Good luck and as Larry says - more info please / keep us posted. Larry is an absolute wizard and I love to see the NSX version of Sherlock Holmes at work.

 

[nsxtasy]

Also, I have noticed that in first gear, the rev limiter has been kicking in at 7000 rpm. Anyone run into this kind of problem?

As Larry correctly notes, the rev limiter will kick in at 7000 (actually, I think it's 7100) when the engine is cold. This is normal.

Does the rev limiter still kick in at 7000 when the engine is fully warmed up to operating temperature? If it does, that is a problem.

 

[pattejam]

ok,

I am going to rip into the motor tomorrow. I have a bit a experience inside engines, having done 3 head gasket repairs for my self and friends. I will check all these and see if there is anything obvious under the valve cover. The early rev limiter thing has been going on for a while now (1 month) and it is only in 1st, so i wrote it off as a bad sensor or something.

I will get all the info together and I want to thank you guys. It is always helpful to speak to someone knowledgable. The local Honda dealership is a joke and I am afraid to even take it to them considering the mechanics come out and mention how they never see NSX's.

Thanks
Cory

 

[dustin]

Sounds like you lost a lot of oil and managed to spin a bearing.

 

[Larry Bastanza]

Cory,

One typical oil problem with these engines is a bad oil pump gear due to overrev. They shatter at about 9K RPM. Any missed shift?

The rev limiter may very well be a coolant/sensor issue since the ECU may THINK it is cold. I would not do any "revving" to 7K until you know you have oil pressure.

Good Luck, keep us posted.

LarryB

 

[Juice]

Re: Re: Engine woes

As Larry correctly notes, the rev limiter will kick in at 7000 (actually, I think it's 7100) when the engine is cold. This is normal.

Does the rev limiter still kick in at 7000 when the engine is fully warmed up to operating temperature? If it does, that is a problem.

I did not know this. This explains a lot as I thought the rev limiter was fixed at 8000. Thanks!

 

[MvM]

pattejam

Search for oil-pressure related problems here in Prime. It seems there are and have been many cases of the oil-pressure gauge reading 0 all the time without it having any effect on the engine itself. As stated above, the gauges seem not very accurate and different cars have different readings all the time.
But, then again, you should be better safe than sorry so please do your check-up and let us now the results.

 

[dlongo]

Hi,

since the oil pressure sending unit is notoriously inaccurate, you may want to check oil pressure using a good pressure gage tapped into the system. The procedure is on page 8-5 of the service manual. Pressure should be 69kPa(10Psi) min at idle, 343kPa(50psi) min at 3000 rpm. Good luck.

Dave

 

[pattejam]

Alright,

Well after a busy week, I was finally able to spend some time out in the garage.

I changed the oil and noticed no water or anything suspicious in the oil. Also the coolant looks fine. There is also no oil leaking from the motor or on the outside. I guess the smoke was a small bit burning off from spilled oil. (When it happened, I did add a quart in the dark).

After firing it up, there is a small bit of pressure (less than normal) and a distinct knock from the bottom of the motor. I am starting to accept that i might have spun a crank bearing.

I always run synthetic in the engine, but when Acura did my timing belt / water pump, they put regular in. Is there any problem with doing that?

Assuming it is a bearing, anyone know what the repair might cost? Am i looking at a full rebuild?

Thanks
Cory

 

[4AU4LIFE]

I don't think mixing regular oil and sythetic is good but if you are changing it you should be alright. Someone please correct me if I'm wrong.

 

[Larry Bastanza]

Cory,

I just re-read your original post. "Full Throttle" run to 50MPH. I apologize for the stupid question, but when did you shift to second?

This really sounds like an over rev, since it seems sudden, although I recall some folks mentioning their oil gears just "broke". I think you will need a rebuild, at least the lower end, which we lead to a complete tear down to do it correctly.

I would suggest calling Basch Acura about this. Also ERZ motors will have a used motor if you need it, as well as the forum wantads. I saw an entire drivetrain recently for sale,at an attractive price.

HTH,
LarryB

 

[pattejam]

OK,

My baby is heading out to the acura dealership tomorrow. I think this issue is well out of my area of expertise.

I will keep everyone posted.

Cory

p.s. Anyone got a good used engine for sale, just in case.

 

[4AU4LIFE]

I saw one on ebay a few weeks ago. Although the seller wasn't very helpful about giving good information or pics of the product he was selling. I was thinking of buying it but decided against it when he denied pics.