Oil pressure tb42

[shortgq]

Hi, new to the board and chasing some information.
I recently bought a ford maverick (aka nissan patrol) with the tb42 petrol motor. I know i need to spend some money on the engine on basic stuff but i do have one concern. The motor misses but i know the carburettor has a flat spot. It has done 246000 k's. My concern is the oil pressue. When started the light goes out pretty much immediately and the guage rises to about 3-4kg at idle. Now when the revs rise sometimes it stays at the same pressure and sometimes it drops to 2kg approx. while sitting on a steady 2000 revs say highway cruising. Maintaining the constant revs the guage seems to fluctuate between just under 2kg to 4kg. I have replaced the oil and filter with no difference. I have heard that these guages may be inaccurate or do u think it may be mechanical problems. I'm not to concerned if there is too much wrong as i was aware that i would need to spend money on it, but i would prefer to spend on repairing something small rather then a motor damaged with low oil pressure.

Sorry for the long post but i would appreciate any advice or similiar experinces.
Thanks Guys

[matthewK]

more then most likly that the guage is a bit on the odd side just keep checking ya oil every now n then keep ya eye on the oil light
mine dose the same every now and then

[buger man]

my gq desiel did the same thing replaced the sender semed a bit better i then put penrit hpr deisel 20w60 in it , the gauge went crazy for 2 weeks then every thing setteled down now idle's at 2 and runs at just under 4 .
i think the relef valve was sticking and the thicker oil made it open abit more eventuly freeing it up i now run penrit 15w40 with no problems
the motor has done 130,000

[bazzle]

As above and Yes the senders on these and the diesels play up a lot.
A new sender normally fixes problem for about $100 genuine.
Worth it for peace of mind.
Oil pressure is not high on these when hot.

Bazzle

[GQAndrew]

Oil pressure is not high on these when hot.
Bazzle

What sort of oil pressure should you expect Bazzle, according to the Gregorys manual it says

idle - greater than 11 PSI
3000 rpm - 42 - 57 PSI

Is this when warm? Is it a reliable guide.
I just installed a mechanical gauge and when hot reads about 19 PSI idle, and about 42 reaching 3000 rpm, so I guess Im at the lower end of the 3000 guide.

[bazzle]

from 1 on the guage at idle hot to between 3 and 4 at 2000 hot

May read over 4 cold until bypass comes in or oil thins down

Bazzle

[Roctoy]

my TB42E does the same thing.
I just ignore the gauge, there's plenty of oil in it.

Check it reg.

[Brunsy]

Dont worry yourself over it, the nissan guages are not the most accurate. If the light is going out the pump is making good pressure quickly, this is a good sign as a shagged pump will struggle to get the light out and maintain pressure. If you want confirmation get a mechanic to use a mechanical guage to test it. My SWB has done 300 000k and the guage has allways read low. I found as will all the nissan engines i have built and owned Valvoline XLD keeps them happy and quiet and its comparitively cheap.

Also interestingly enough most wreckers have a fair few TB's bottom ends sitting around as they just dont give any hassles, the heads on the other hand usually show signs of stress around the 250000k mark, just replace mine, cracked and valveseats pounded in.

All in all they are a fairly good little tractor.

[Guy From Nowhere]

Hey all,

Bit of a grave dig I know, but seemed best to keep oil pressure talk in the thread linked to the GQ Bible.

THE PROBLEM: I have a 1991 petrol GQ and the oil pressure Issues I have are a little reversed from the ones above. Cruising on the highway (AC/DC style) I get a reading under 4 but closer to where 3 would be. When I get to the lights, so at idle, it drops to well below 2 and the oil light comes on.

From what I can gather from reading above, my oil pump should be in good nick, due to the light going off very quickly after the revs go up (after take off from idle). Hence, the pump is creating pressure quickly which would indicate it is working: is this right?

So, do I worry about my gauge or do I concern myself with the engine? It appears to have a small oil leak, but the oil only goes down very slowly (I driven it 3000km with only one ml difference on the dipstick). I am going to change the oil and filter to see if this makes a difference at all also.

Cheers
GFN

[ZAPPA]

GFN
The oil light should NOT come on at all once the motor is running, If my oil light was doin that I would be worried. If the oil pump seems to keep up at revs there would have to be somewhere in the motor that the clearences are too big, hence when its just idling the oil is escaping faster than what the pump can supply. Does it do any knocking or anything? Might be time for some new bigend and main shells!! Unless of course the bypass spring is not seating properly. I dont know what the patrol lights are set at, most are set at 5ps1 or something, I would be doing some investigating.

[PGS 4WD]

I was replacing oil senders in these as an apprentice under warranty in 1994 when I started, they are not accurate.

Joel

[naif]

id have to check my gregories manuel, but does the oil pickup on the tb42 and td42 have an o-ring seal? if so this could be a cause of low oil pressure, very common in most engines.

[chimpboy]

The oil pressure guage in a GQ is a piece of junk that is frequently rooted.

[ZAPPA]

I dont know about the o ring in the pick up. There are plenty of galleries on the side of the block that will give you a correct reading. Dont use an electric gauge, get a decent mechanical or capillary gauge and find out what is goin on. If the motor is running and at idle the oil light comes on there is something wrong!! If the o ring was gone on the pick up I would guess that on a cold start after sitting it would struggle to suck the oil up. If its cold does the light still come on or is it only when its warmed up?

[NutterGQ]

i run a mechanical gauge and the original still wired up (RB30) the factory gauge sits in the same spot the mechanical goes from 15psi at idle to 55-60 at 2000rpm and above when hot.....moral here factory gauge is a bucket o crud.

[Guy From Nowhere]

Thanks for all the help thus far. I finally got some time under the bonnet and discovered a few interesting things. The ignition leads ar original and so were the spak plugs by the look of them I know this has nothing to do with oil pressure, but it is on the way. I had to take the Air filter and box out to get at the spark plugs - they were almost welded in. When the box was off I noticed oil had been leaking out of the top cover at the rear. Based on the originallity of all the parts, I decided to get the screw driver out and check the fastners. They were almost finger loose! I then located the another minor leak from the front end and found some more loose bolts! The old girl hasn't been serviced from birth - the joys of secondhand vehicles.

Now, I can't say just yet whether this has changed my pressure, I assume it would, because I can't get the bloody oil filter off. Does anyone know some neat tricks for their removal? Have already stabbed it with a scer driver, but am finding it hard to get my arms in to change it. I must say Toyota were a lot easier to change, pity bout the vehicles hey

[msjc38]

Before blaming oil filter brands put oil pressue master gauge on leave it for a night before starting. Then you will see exactly what is happening when you start up.

[Guy From Nowhere]

G'day, g'day,

Well, I got everything back together and changed over in the filter area. With the new oil filter, new oil and freshly tightened rocker cover she went well (of course the new spark plugs and leads would have helped). I drove aproximately 80 km of city driving, which would have covered all ranges of revs and oil pump opperation. She now sits happily on 4 at the higher consitent revs and drops down to slightly above 2 when idleing. And guess what? No more oil pressure light!