Low Oil Pressure causes

[Gerardjg]

This is a continuation of the oil leak thread zer...begin I need some advice. After my Cam shaft seals were replaced and the engine reassembled, I was told my oil pressure is at 2 psi Idle and 12psi at 2000 rpm. The Shop is telling me the wire was broken on the Oil Pressure switch. they replaced the sending unit repaired the wire and my oil psi light is on when the engine is running. My total bill is 2k and the car is not drivable.

Is there anything they could have done when replacing the cam seals and timing belt to cause low oil pressure? I did have a leak loosing 1/2 quart per 100 miles but I only drove it 200 or so miles with the leak checking and adding oil every 30-50 and it was never more the 1/2 a quart low. Could this have damaged the engine as the shop is saying.

What drives the Oil Pump is it geared or driven by the timing belt?
Modified by Gerardjg at 4:47 PM 1/25/2010

[Infinitiguy19]

So they ruined the car and still want 2K dollars?

I would not give them a penny and consult a lawyer.

But this sounds more oil pump related unfortunately I am not familiar with the VG30DE so I can't be of much help. I looked at the service manual for a little while and I don't see what drives the oil pump exactly.

[yodawill2000]

If I'm not mistaken its driven by the crankshaft.Not the Timing belt.

[Gerardjg]

That is what the shop is telling me, what they did has nothing to do with the oil pressure. My drive to the shop with the oil leaking could have caused excessive wear.

I did speak with an attorney he said I would have to prove they were at fault. This would involve taking the car to another shop or expert have them tear down the engine and try to prove cause. The shop I am dealing with is the local expert very reputable, and always packed the owner does the local automotive talk show in the Orlando area. It is just going to hurt to give them 2k and have the car towed back to the house.


Modified by Gerardjg at 2:56 AM 1/27/2010

[qship96]

if it is similar to the Q engine, the crankshaft pully bolt must be correctly torqued as it drives the oil pump-too loose and you have oil pressure problems!

[GerryO]

Figure the oil pump (15010) is driven directly by the crankshaft.



Seems like a broken wire from the oil pressure sender should have caused the low oil pressure light to be on constantly.

How did they obtain such precise oil pressure readings and they are saying that low oil pressure did damage to the valves and camshafts?

The oil pump (about $175) can be replaced.

Accumulated sludge in the oil pan could be clogging the strainer assembly (15050) inlet.
Modified by GerryO at 5:50 PM 1/26/2010

[GerryO]

if it is similar to the Q engine, the crankshaft pully bolt must be correctly torqued as it drives the oil pump-too loose and you have oil pressure problems!

The J30 pulley is keyed on the crankshaft, the bolt just keeps things tightly in place and the oil pump sits behind everything.

[Infinitiguy19]

How did they obtain such precise oil pressure readings and they are saying that low oil pressure did damage to the valves and camshafts?

If they hooked up a accurate oil pressure gauge to the oil pressure sensor hole and got 2 PSI at idle and 12 PSI at 2000 RPMs then your engine is toast, I am sorry.

If I were you I would ask them to replace the engine with a equal millage engine or LOWER!!! Bring them any recipts you have of work that was done to the engine so they can do the same before the engine goes in as well. Better yet just take the money and run to another shop that can do there job right.

[1994 infiniti j30 190+]

if it is similar to the Q engine, the crankshaft pully bolt must be correctly torqued as it drives the oil pump-too loose and you have oil pressure problems!

not entirerly true a little while ago i had my crank bolt losse idk for how long but found out it was loose and i had driven my car for a long time it it acted just normal nothing different so loose bolt cant be the issue.

[qship96]

Oh really............. might want to double, triple check relationship between proper torque of crank bolt and oil pump drive slipping......it just may save an engine

[Gerardjg]

If they hooked up a accurate oil pressure gauge to the oil pressure sensor hole and got 2 PSI at idle and 12 PSI at 2000 RPMs then your engine is toast, I am sorry.

If I were you I would ask them to replace the engine with a equal millage engine or LOWER!!! Bring them any recipts you have of work that was done to the engine so they can do the same before the engine goes in as well. Better yet just take the money and run to another shop that can do there job right.

They want me to give them 2k for the timing belt and sprocket replacementsand do not recommend I drive the car because the oil psi light is on.

[yodawill2000]

The crank pulley should be torqued to 160 Ft Lbs.

But like GerryO said it is keyed.Maybe the key came out when they pulled the Pulley for the TBelt change ?

[1994 infiniti j30 190+]

Oh really............. might want to double, triple check relationship between proper torque of crank bolt and oil pump drive slipping......it just may save an engine

i know we torqued i befor it was loose and we did when we retightened but i think my motor is starting to go anyways hearing way more than normal ticking under the hood than i had befor so i may need a motor soon either way.

[Infinitiguy19]

They want me to give them 2k for the timing belt and sprocket replacementsand do not recommend I drive the car because the oil psi light is on.

Your missing the point, THEY DESTROYED YOUR ENGINE!!! Was your engine running fine before you took it to them?

i know we torqued i befor it was loose and we did when we retightened but i think my motor is starting to go anyways hearing way more than normal ticking under the hood than i had befor so i may need a motor soon either way.

I think you may have starved the top end but again I am not familiar with the VG30DE. If you guys have HLA's then look into that.

[StevenRNicholas]

If they will not budge on the price or taking ownership of the problem then pay them. Tow the car home. Talk to a bunch of mechanics 5 or more if possible and tell them your story. Try to get a mechanic or engineer friend to go with you. Do not do anything until several places have been contacted. Ask them what they think the problem is and what they would do to fix it. Then pick the best one and have them repair it. When it is all fixed, pay the shop and contact the original shop and tell them what happened. If they still blow you off then look into small claims court and drag them in front of a judge and tell the judge what happened. God speed.

[StevenRNicholas]

Oh and document everything. Wright everything told to you and note names and time and dates. Get signatures for as much of the info as possible. Collect all receipts, even for towing. Don't cheat on anything. Take all of this and your mechanic or engineer buddy, if possible, to court with you. You may only get one shot at the judge so go prepared on the first trip. Be calm, professional, and polite to every one. You should claim that the $2,000.00 was fair for what they did but the damage was not. The judge will not like hearing that a local shop is this callous. He may only make them pay your repair costs but that is better than nothing.

Search for how to do small claims in your area. Also see the maximum amount the court can award. It should be more than you have spent or you should go to Big court.

I was having trouble with a Sears charge card once (90's) and they would not correct their error after 5 months of on the phone promises. I calmly just stated on the phone to the umpteenth rep "I guess we will have to go to small claims to get this straightened out." They fixed it then.

[GerryO]

Request an engine diagnostic print out that includes the engine timing and TPS output voltage numbers, and also a compression check of all six cylinders. They replaced the timing belt and should have checked/set the engine timing. Top-end noise and low compression numbers would suggest that they may have bent a few valves, as a result of screwing up a timing belt change on the interference engine.

[Gerardjg]

I finally had the car towed to the house, I started it and it sounded normal and as quiet as it ever was, revved it up slowly a couple of times no noise no oil pressure light. Brought it up to about 4500 rpm still no noise. I let it idle and after about 2 minutes the oil pressure light began flickering and the rattling began I immediately shut it down.

I started it again about 6 hours later and got the same results

The next couple of weeks I am busy with life but I will get back to it and will start pulling the Crank shaft to see if the Pump is engaged. They offered to pull the oil pan and check the pressure regulator but I decided to get it home.

[driverdriver]

Do you have a VG30DE specialist in your area? There has got to be a 300zx club somewhere in Florida, where (a.) members are well versed in our engine (b.) who know a reputable 300zx engine specialist.

[GerryO]

Start simple: - aerated oil due to over-filling - restricted top-end return holes - sticking oil pressure relief valve - plugged oil filter - worn oil pump - clogged intake screen - excessive bearing clearances

Lots of good reasons to change your oil regularly.

http://www.aa1car.com/library/us1097.htm

Among other things note the DIAGNOSING LOW OIL PRESSURE section.

Sounds like your oil pressure might be OK until the oil warms and thins, gets frothy or it's pumped up top, where it doesn't drain back into the pan quickly enough.
Modified by GerryO at 9:12 PM 2/4/2010