I do not drive my Zed on a daily basis, sometimes it may be several weeks before I give her a run out.

If she has sat for a couple of weeks and I start from cold, (garaged) the revs hit 1350rpm and there is a very audible machine gun type rattle for a couple of seconds. I am running 5w-40w fully synthetic top of the range oil, and although the bottom end has only done 25,000 mile, the top end has done in excess of 133,000 miles. Am I running a risk of doing damage? What might the cause be?

Any advice would be very much appreciated.

that oil is way to thin.... at the very least 10W40 Semi... but better off with 15W40 semi.

empty it out and try again with thicker... see what happens then....

I think its reving to high on start up mine revs at 1000rpm from cold then goes down to around 750 when warm (aircon off) Plus I dont like it ticking over for long periods its much better taking it for a gentle drive.As for oil I am not to shure so will let the experts post on that.

my info is from the word of JeffTT.... I'm sure there is no higher... lol.. :)

noisy lifter? i have a very annoying noisy tappet, it goes after a while but can come back even when the engine is warmed up and the oil flowing about. but does go again on its own accord.

that oil is way to thin.... at the very least 10W40 Semi... but better off with 15W40 semi.

 

empty it out and try again with thicker... see what happens then....

 

No it's not too thin mate - a 5w40 oil is exactly the same as a 10w40 oil once up to running temperature....!! See one of Oilman's many threads on the subject; the lower number before the "w" indicates the oil's ability to circulate quickly around the engine from cold. The lower the number the quicker it will get round during a cold start. The "40" bit indicates the same viscocity once at operating temperature; and its ability to resist thermal breakdown

 

Granted, we hardly ever need anything lower than a "10w" with the winter temperatures we see in the UK, but most readily available fully synthetic oils do come in either "0w" or "5w" nowadays. If you want a genuinly thicker oil then you'd have to go for 10w50 or even 10w60. Although the latter is not really necessary unless you're running a highly modified 300zxTT and use it heavily on the track...

 

Richard:cool3:

I do not drive my Zed on a daily basis, sometimes it may be several weeks before I give her a run out.

If she has sat for a couple of weeks and I start from cold, (garaged) the revs hit 1350rpm and there is a very audible machine gun type rattle for a couple of seconds. I am running 5w-40w fully synthetic top of the range oil, and although the bottom end has only done 25,000 mile, the top end has done in excess of 133,000 miles. Am I running a risk of doing damage? What might the cause be?

Any advice would be very much appreciated.

You have asked two questions here. Let me attempt to answer them one at a time.

"Am I running a risk of doing damage?". ...... Well the clever sounding answer is no. Why?? Cos the damage has already occurred.

If you now ask the question" Will I run the risk of doing MORE damage?".. then the answer is yes.

this leads on to your second question. "what might the cause be"..... The machine gun noise if you have described it correctly is caused by metal hitting metal..

Now you want to know which bits of metal... Well In my experience the sharp machine gun noise is usually little ends ie gudgeon pins in the rods/pistons. Its cause by excess clearance(WEAR) and is the sound of metal hittting metal.

If on the other hand it is a tapping type noise then lifters are the suspect.

Bottom end noise is usually deeper in tone and is normally Main bearing and big end bearing wear.

 

Changing oil will never cure wear of metal components. Heavier oil might mask it for a little while.

Changing oil/flushing is often a solution for noisy lifters tho. So worth doing to rule them in or out as the root cause.

In all problems like this you need to look for the root cause ..... not treat the symptoms

 

All of course IMHO:closedeyes:

I start from cold, (garaged) the revs hit 1350rpm and there is a very audible machine gun type rattle for a couple of seconds. I am running 5w-40w fully synthetic top of the range oil,

 

Most if not all zed engines that start easily will rev up when cold and cause a slight rattle as the oil pressure takes a moment to equalise, however any more than that points to other issues, some a concern some not so.

 

A bit more investigation is needed to establish more closely where the noise is coming from, on the next cold start have the bonnet up and see if you can establish if it is a general sound ( normal ) top end ( lifters ) or at the middle front of the engine cambelt top pulley bearing.

 

In the meantime drain the fully synthetic oil and change it for 10w-40 Semi Synthetic, paying for fully synth is not necessary and can promote oil leaks on older engines with less than perfect seals

 

 

I think its reving to high on start up mine revs at 1000rpm from cold then goes down to around 750 when warm (aircon off) Plus I dont like it ticking over for long periods its much better taking it for a gentle drive.As for oil I am not to shure so will let the experts post on that.

 

Tickover speed when cold is regulated by the dediicated cold start unit, this can stick sometimes keeping tickover high even when the engine has warmed up, high revs when cold can often be corrected by cleaning the valve out.

 

 

No it's not too thin mate - a 5w40 oil is exactly the same as a 10w40 oil once up to running temperature....!!

Richard:cool3:

 

Common misconception, thin oil, thick oil, abient temperture conditions ( Winter or Summer) many of these are left over from early motoring times, when cars need the heads taking off every 20k miles to decoke the engine and a blind was fitted over vthe radiator in Winter etc, all of this adds confussion to an already confusing subject.

 

Modern engine oils can do it all now with out the need for all of the old school trickery, however I do agree 5w is "too thin" by that I am not talking about viscosity but the molecular structure, smaller structure can flow quicker but it can also leak down quicker back to the sump, leaving lifter valving compromised unless they are in top condition, a "thicker" oil will be less likely to cause the same problem.

 

 

 

Oil choice is a very emotive subject and asking 10 people will often get 10 different answers as different cars deal with the changing temperature ranges and load in different ways such as a 3 litre TT Toyota engine will be different to Nissan 300zx engine despite same engine size, comes down to how they are built, many engine oil charts will reccomend just based on engine size and not on an individial basis as the application chart would be like "War and peace"

 

A middle of the road oil is not a compromise but a real world application for lets face it 20 year old engines that need a little lift here and there.

 

Jeff TT

Thanks guys for the valued input,

I can only hope that it is something less serious than the little ends. Albeit on the face of it, it does appear so.

Still, a few things to try as suggested with regards to perhaps running a thicker oil.

In addition to changing the oil, I will see if I can get the initial start up revs to be lower by way of cleaning the related valve as suggested.

 

One thing that might be worth a mention is, last year before I changed the oil, I ran Wynne's lifter treatment for a few miles with the hope that it would quieten down a light tappety noise. It did seem to be better but did not disappear entirely. Would this have had an affect on the new oil I then added?

 

With regards to starting from cold Jeff, she does fire up very quickly, almost instantaneously! so you have given me hope with regards to it being more oil related than mechanical, as you say, considering the age and mileage. I will take your advice along with everyone else's and do a bit more investigating so as to try and determine just where the noise is coming from when I next start from cold

 

Picking up on the cold start RPM, Once a couple of minutes have passed, she does settle at a rock solid 750rpm and only rises slightly when I engage the air-con. Would there be a way off adjusting the initial cold start RPM? or is it a matter of cleaning or replacing?

 

In the meantime I need to choose a thicker oil, would Mobil 1 be worth tyring? or would anyone suggest something different?

 

Again guys, Thanks for the support thus far, particularly the more in depth replies.

I appreciate the time you have taken to advise me.

 

ps Is there a particular trick as to draining the oil so as to make sure I get every drop out? I am looking at leaving the sump plug out for a week or so.

When i owned my zed i had the problem of the car started too easily and after it had laid for a week or so and top end oil had drained away i had the "rattle" explained in this thread but as soon as oil pressure built up on my gauge after a second or two it instantly stopped. One of a couple of jobs i was going to undertake but sold the car before was to put the fuel pump fuse via a dash mounted switch which could be de-activated on start-up but as soon as oil pressure come up then "flick" and bring in the fuel pump thus reducing a dry top end being burdened with 1200 RPM on start up....something for you guys with the same problem to consider.

Edited September 23, 201212 yr by znut

i'm certain i've got lifter tick.. 200yrds down the road, and its gone. plus the car tends to sit for 1 week or 2 between outings. I used it 2 days on the bounce for the first time ever and she didnt tick at all on day 2. and i also have a weapy crank seal. semi synth coming up then! on a positive note though, the weaping oil is still golden.

 

i'm interested in this high idle fix though? mine tends to sit at 1200rpm no matter what. more info on dedicated cold start unit please?

i'm interested in this high idle fix though? mine tends to sit at 1200rpm no matter what. more info on dedicated cold start unit please?

 

Hi John,

 

right, high idle can be down to a number of issues and there isn't a magic "high idle fix".

 

If a car was an auto and has been converted to a manual but still has the auto ECU without grounding one of the wires (can't remember which one) it will cause high idle.

Other causes can be ECU temp sender unit not working (the one with two wires), bad IAA unit and/or other setting wrong (to name a few).

 

 

first the car should be kept maintained, filters, plugs, oil (but you're on that), all connectors checked and cleaned (i.e. no corrosion and correctly seated).

TPS should be set to between 0.4 and 0.5 V (0.45 is good, I think it varies for auto to manual).

Timing should be set with a timing light to 15 TDC, adjustment is done by turning the CAS unit.

Once these are set right then the idle screw can be adjusted to the right amount (best to use consult to see accurate revs but can be done OK using the taco).

 

check in the Tech FAQ's (on this forum) for info.

this is a guide for idle adjustment also a good site for info:

http://z32.wikispaces.com/Idle+Control

FYI... turn car off before connecting AAC plug, then back on to adjust.

Also here for guide (and another good tech site):

http://www.pexcom.com.au/z32cms/e107_plugins/content/content.php?content.335

and another great tech site...

http://www.twinturbo.net/nissan/300zx/tech/tech.aspx

ok, well shes an auto, has had that idle on 2 different ECU's, the idle isnt lumpy, so i'd be surprised if the timing was an issue, she runs smooth as it gets, doesnt miss a beat. no pinking or the timing related issues that I'm aware of, so probably temp sender or IAA a good place to start. I'm not gonna mess with the TPS at the moment after seeing the cuffudle thats arisen with voddy's although it could be unrelated.

 

i'll read the faq's and thanks for the pointers ;)

ok, well shes an auto, has had that idle on 2 different ECU's, the idle isnt lumpy, so i'd be surprised if the timing was an issue, she runs smooth as it gets, doesnt miss a beat. no pinking or the timing related issues that I'm aware of, so probably temp sender or IAA a good place to start. I'm not gonna mess with the TPS at the moment after seeing the cuffudle thats arisen with voddy's although it could be unrelated.

 

i'll read the faq's and thanks for the pointers ;)

 

Timing out doesnt produce a lumpy idle, but can invoke quiet pop's from the exhaust and a sensation of it misfiring with out the loud pop, ill have my timing light on me on friday (hope we have nice dry night) i can check the crank timing for you if you want.

A bit of an update, I had a chat with the previous owner yesterday, and he confirmed that he replaced the complete engine complete with turbos, not just the bottom end as I first thought. This means it has covered only 22,000 miles, hopefully this would suggest that the little ends are good? With that in mind I am clinging to the fact that a thicker oil may be the resolve. Puzzled as to why though given the mileage.

Maybe the use of the lifter treatment is still playing it's part.

 

Looks like an oil change is the next step. As earlier, any advice as to which oil I should consider?

I put 5w40 full synth in mine and it started smoking, oil was too thin causing it to push thru pcv system, so changed to semi 10w40 and 50 miles later all is good, I used 540 because of new bottom end but you must remember other oil fed parts are still old in my case turbos and various other comps, so stick with 1040 or 1540 you cannot go wrong.

Cheers Flegal.

I will be shopping for some 10w 40 at the weekend.

May drain the oil and leave it for a week or so to try and get every last drop out.

Just hope I do not loose the blo*dy sump plug. lol

Cheers Flegal.

I will be shopping for some 10w 40 at the weekend.

May drain the oil and leave it for a week or so to try and get every last drop out.

Just hope I do not loose the blo*dy sump plug. lol

 

give it a wipe and put it in the ash tray...or are you jesting?:confused1:

Top tip znut,

it's just that I tend to have a habbit of putting things somewhere safe and then forgetting where I put them.:lol:

Top tip znut,

it's just that I tend to have a habbit of putting things somewhere safe and then forgetting where I put them.:lol:

 

i have the same trouble with the wifes housekeeping money at the w/end mate:rofl:

Nice one!!:lol::lol::lol: