well, my maxima used to get max pressure which was around 20 or so PSI when it was high up in the RPM's and i could hear alot of noise from the lifters, so i thought ill just put another quart in the car since it sat for a long time, probably doesnt ahve enough oil in it. so i put the extra quart in and now the pressure gets around 30 PSI or so and the lifter noise dropped down a little bit, but its still there, so i fugure ill check the dipstick and see how the oil level is, and its incredibly high. anyone have any thoughts?

 

You obivously didn't check thee oil before you added the quart!!!!!
Have you changed the oil? If not change it and put in the correct amount of the heaviest grade oil for the engine per the owners manual, and see what the pressure is. If it's still very low you may have to live with it! Earl

 

Lifters are probably gummed up from sitting. Nice thing about these L-series engines is that the oil pump is very easy to get at. Upgrade to the 280zx turbo oil pump for more pressure. Well it SHOULD be easy. But this is for someone that adds oil without checking the level first.

I'd try some Seafoam in the oil ie.. 1/3 bottle about 100-150 miles from the next oil change. That might clean off the varnish from the lifters and quiet them down

 

I'd try some Seafoam in the oil

I keep reading about "Seafoam"? What is it, and where can it be purchased?
Earl

 

same here

10

 

What year is the car? If you have a L-series:
YOU NEED TO DO A VALVE ADJUSTMENT! (cold and then hot: see Nissan FSM). It will make a very bad sound from the head if they are really out of adjustment. You should adjust several times every year.

The stock pressure relieve valve opens at 50psi. it depends on what oil you use, so pressure will vary.

The 280ZX turbo pump is good, but you can get excessive wear on the front cover/ pump drive shaft. I run one in a NA L28 and it get good pressure, but I have not torn into the motor to see if the above has taken place. The turbo pump has extra volume for the oil going to the turbo.

Only the 83 ZX Turbo (L28ET with P90a head) came with hydraulic lifters. I had a 84 Maxima and it had mechanical lifters.

 

yeah its an L series (year 82), but dont they have hydraulic lifters?

 

No 810 or 910 has hydraulic lifters unless it has had a P90a head installed. You can look on the right side of the head toward the front and just under about the number one plug there will be a letter and a number cast into the head ("casting number"). All 810 and 910 in the USA market had the N47 head. This head has mechanical lifters only. I had an 84 and it had the N47 head with mechanical lifters.

Note: there are several versions of the N47 head. The "N47 Maxima" head that came on the 810 and 910 were the best for compression increase on the z-car engines); Z-cars had larger chamber N47 heads with lower compression heads (on stock pistons dished/flat). The N47 Maxima heads have a chamber that is like the good ones found on the P90/P79 heads, but with a small chamber for compression. They also have exhaust liners, but if these have work done to grind the liner base flat and smooth with the valve seats then the liner will help the exhause gas make the turn in the port instead of slamming into the chamber's top as with the other L-series heads.

Also note that there are two versions of the P90: the standard P90 with mechanical lifters that came on the 81-82 280ZX Turbo.
The other version is the P90a with hydraulic lifters that was only used on the 83 280ZX Turbo only. NO OTHER L-SERIES USA MARKET HEADS (and all other markets as far as I know) came with hydraulic lifters.
There is also a P79 head that came on late model 280ZX non-turbo cars. The P79 head was used with the flat-top piston L28(E) and has the same design as the P90 but a smaller chamber than the P90 (but still not as small as the N47 Maxima head).

The P90 is probably the best L-series head that Nissan ever made (at least for turbo). In terms of reasonable compression heads the P79 is the best. But, with the correct work the N47 Maxima head is the best for real compression without shaving the head (something to avoid if you can. Shaving the head should be the last resort to get compression).

 

i dont happen to have an fsm, so would someone mind saying what the specs are for the valve adjustment?

 

so does no one have an fsm, or does no one want to share?

 

I do, but I have to find the manual first:} By the way, if you go to zcar.com, there is a nifty slide show on valve adjustment for the L24

 

If you mean the Valve Clearances when the engine is hot, they are for Intake 0.010 in (0.25 mm) and for Exhaust 0.012 Inches and (0.30 mm). Hope this helps.

 

There is a P-99 head I gave to datsun dynamics.

It came on one of the last 280zx turbo 5 speed manual transmissions.

I can find no difference between it and the p90a.