oil to thick? gq

Andy
Have a 2003 GU 4.2TDi and run 20W60. Haven't had any overheating problems (even when pulling 1.5 tonne van). Nissan recommends 20W50.
Brid bearing in mind Nissans recommendation of 20W50 do you consider 20W60 to be a cause for concern? I'm upgrading to a 2.8 tonne van shortly so may have to reconsider my oil options.
I used the same oil (20W60) in my Defender for 5 years towing the same van and never have problems with oil (everything else tended to fall off but the oil was always spot on a the 5000km changes)

Peter
I don't think there is any cause for alarm as far as lubrication protection goes in this particular type of engine. In addition, oil degradation due to shear out of viscosity index improvers will be less of a worry than for a lighter weight oil. Cheap oils often drop out of specification (to a lower viscosity) during the recommended oil service period, so you can lose protection.

My comment above relates to optimizing performance...providing the highest viscosity for protection, without causing excessive fluid shear (which can elevate oil temp) and horsepower losses due to fluid drag.

Warthog,

Although I agree with you in that he is using the wrong oil and I also agree with the document from Caltex, the TD42 is not a typical Japanese engine.
IN fact if you look at the table of differences at the end of the document you will find that the TD42 fits the american engine design more than the japanese design, this is because the td42 engine design was initially copied from the Perkins engine for use in small trucks and buses in the 80's (like the civilian) bus still being used today.

Also if you examine the pistons from a td42 engine, they fit more closely with the american design. The sump capacity to power ratio and service intervals also reflect that of american designs due to carbon deposits.

Will

I am not a mechanic and have not seen the pistons on a td42 so I'm happy to stand corrected on piston ring location. The caltex tech I rang though was adamant their primary recommendation for my td42t was delo cxj. I understood the reason nissan specs 5k oil changes for this engine was that the typically american biased formulations in the diesel oils on sale in Aus dont handle the soot loads the td42 generates.

I can (once I get hold of it) post a picture of a TD42 piston.

In fact, a few years ago we had a perkins motor and a td42 side by side (pulled apart) and although Nissan had made some significant changes to make it a faster revving, more modern engine, the similarities were amazing!!
Nissan has modernised this engine even more when they added a turbo to it in 1999, ie: lighter pistons, different camshaft and injection pump in an attempt to get it to comply with emissions.

Seeing as how my name has been mentioned I thought I'd better throw my 2 cents worth in at this point.

I firmly believe there are 2 separate, and largely unrelated issues here.

1. The grade oil being used.......I'm no expert but I would not be using that grade (or brand) of oil. I now use 100% synthetic AMSOIL and have just sent a 4th sample off to the Castrol Lab for analysis, with the oil having done 25,000klm since it was put in the motor. This oil is 15W40 and the next lot I have ready to instal when needed is actually 5w30.

I am not convinced the oil grade/type/brand being used is a cause of the motor getting warm.

2. The TD42 does get warm......get used to it!!!! hahaha I have gauges for all sorts of things in my cockpit. One of them is a VDO water temp gauge; sender is in top radiator hose. On an occasion at New Year when it was very hot, I managed to drive about 250klm or more with the standard gauge just below the 'danger' zone on the right side of the gauge. Meanwhile the VDO gauge was telling me the real temp was about 118oC. Okay, that IS warm....but it's NOT "overheating" as far as I'm concerned. I didn't back off from the speed I was travelling (around 100k/h) and I was well loaded up with a combined gross mass of about 4.5T. The truck did not lose power etc and as soon as I was able to get onto any slight downhill section, the temp dropped. All this time the EGT (above the turbo) was sitting on no more than 550oC, which equated to about 430oC in the dump pipe. Note too that I have disconnected the switch in the bottom radiator tank which triggers the air con to switch off if the water temp gets to a certain level...... as far as i was concerned the air con should not switch off when it's a hot bloody day!!!As far as EGT's are concerned, I have never had it hotter than 585oC/450oC respectively. I attribute these relatively low temps to the 3" exhaust system.

So, my advice about the heating situation is not to get too hung up about seeing the Nissan gauge go above half way; at least until it gets into the twighlight zone on the far right hand side. Nissan even say that the vehicle is designed to operate with the gauge going that high and not to worry about it.....I know it is easier said than done!!!!

Hope this helps.

Cheers

Roachie

G'day Roachie, been following your so called overheating for some time now, and I read with interest that you disconected the cutout switch for the A/C at the bottom of the radiator.

Did you just pull the wire off? Or some other fix?

Its a pain when the air cuts out and the needle has only moved a poofteenth. In my case to half or straight up and down.

Tony,

Too easy really........

On the bottom of the radiator there is a screw in plug on either side, each with 2 wires coming out. The one on the passenger's side is the one that triggers first, cutting off the air-con. If you look closely, the 2 wires go to a 2 part plug/joiner that can be squeezed in the right spot to release the lock and then you can pull it apart. This will make the switch inoperative.

I have left the other switch (on the drivers side) in tact. It is designed to trigger at a slightly higher temp and turns on the air-con's electric fan in front of the condensor behind the grill (but the air-con compressor does not cut in). The idea of this is to get some extra air flowing through the radiator to aid cooling.

I have taken this one step further and fitted a 14" Davies Craig electric fan on the opposite side (driver's side) of the air con condensor, which i can turn on at any time with a switch on the dash.

To protect myself from any claims for damage........I must add a disclaimer that this set-up works for me because I constantly monitor my gauges (especially the VDO water temp gauge) and feel confident that I am always aware of what the water temp is. What I would like to do, is to fit another temp sender unit in the bottom hose so i can see how much difference there is between the hot water going into the radiator, compared to the water that has been freshly 'cooled' by passing through it's cores. I have a large PWR radiator (all aluminium) with 2 x 26mm cores.....compared to the standard plastic-tank unit which has 2 x 12mm cores. But after all that, the water is still so hot that if I leave the previously mentioned switch connected up, the air con still cuts out, so I'm not convinced the big PWR is doing any better job than the standard Nissan radiator.

The real unknown issue with some of the 4.2L motors is the story that says there were a number of them manufactured and the casting sand was not fully flushed from the water ways....also the possibility that some of them have had head gaskets fitted without all of the water way holes having been properly punched out. I have no first hand confirmation as to whether either of these scenarios is true or not.

Cheers

Roachie

GUpatrol,
I had a look in the Gregory's manual #519 (the newer one that also covers td42 engines) and it has a picture (pg 117) of a td42 piston. The top compression ring is a fair way down from the top of the piston. It looks remarkably similar to the picture in the caltex document of a Japanese piston and for that matter European which I believed perkins to be. It certainly does not show the piston ring near the top of the piston as is the case with an American engine in the Caltex document. Now I am confused.

There are no diesel engines which have the compression ring near the top of the piston such as the caltex document, I assume they did that for illustration purposes, I would like to challenge Caltex and show them a typical American Allis Chalmers piston or a caterpillar piston and ask them to "explain" their rationale for "american-european-Japanese" document.
However I agree with them on other parts of their document and the need for detergent on certain engine designs but not necesarilly american-european or japanese.

5W30 Gee Proceed with caution, I assume this has been recommended by a Diesel Fitter, running too thin a oil is just as dangerous as running oil that is too thick.

Andrewv> Maybe try HPRDiesal 15>15W50 may be better on the mark, but if Nissan recommend 20W50 I can’t see 20W60 causing that much of a problem.

Nissan recommend 15 w 40

Hi Roachie
I was talking with this mob
yesterday and they faxed through a document which made very interesting reading about water pump pressures, head of water required and head of water available. I was trying to get information out of them about these 4.2 Nissan diesels but I am still waiting to hear back. Aparently they fixed a friend of my mates nissan with head work and a modified water pump. I am still trying to verify it because if it is true I would be happy to work with them and send them work as well as purchase this so called modified water pump off them. I was waiting to hear back from them prior to posting but I thought I would mention it in this thread.
I will keep everybody posted as I emailed them tonight so will check the emails tomorrow.
120scruiser

Just checking my manual for the Patrol (page8-5) and it states:
For hot and warm areas (I live in Queensland so am considering that to be warm) 20W-40 and 20W-50 are suitable. (These oils are recommended for use in temperatures betweeen minus 10 and plus 40 degrees C).
If Nissan apparently can't get the correct oil right, what hope do us mere mortals have?

A friend of mine did the mod from this people to his GQ, water pump, a head modification to get rid of aireation etc etc....

Didn't make much difference.... Well, yes it did to his wallet!!

Peter,
The manual also states that 15w-40 is suitable from -20 to ...... and an arrow that goes to who knows what hot temperatures....

The thing is that the oil plays a crucial role in getting rid of heat from under the pistons, the correct choice makes a big difference.

There was one positive outcome from a fellow in the Patrol4wd forum who had overheating problems using Penrite 20w-50 and his overheating problems dissapeared when he went to Castrol RX super 15W40