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PostPosted: Mon Nov 05, 2018 7:24 am 
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Posts: 5
this is my first post , however ive checked this site a lot in the past and gotten some great info, so first up thanks to the knowledgeable folks who've given their time to help others out.
I very happily own a late 2012 dmax , so its the 12-17 model, 5 speed auto sx 4wd dual cab.
doing the valves next weekend for the first time, got a 1/4 inch torque wrench , welding up a cheap ring spanner and 12mm deep socket, for the adjusting tool, can get rocker gasket and injector seals easy, but a whole kit is hard to find less than $500 , even the guys at bursons are confused by that price. theres some on ebay around $100 but no confirmation they fit my engine version yet.
so questions:
-is 12mm the right size for the deep socket to tighten the adjustment locking nut?
-did isuzu change the injectors on the 4jj1 when they upgraded it in 2012, i thought they just changed to a variable turbo, moved intercooler and reprogrammed it. does this mean that i could buy the full rocker gasket kit for the older version and it would fit?????
-anyone know if there is an oil pan gasket or is it just gasket sealant?

any help would be appreciated


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PostPosted: Mon Nov 05, 2018 8:43 am 
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Joined: Sat Oct 12, 2013 5:36 pm
Posts: 1402
4jj1

A 12mm deep socket is ok but to centre the screwdriver you need to insert a piece of rubber hose so the screwdriver is held centrally when it engages in the adjusting screw slot. I filled the square drive section of the socket with Selleys Knead it, and drilled it to suit screwdriver shaft and blade width. A snug alignment was the result. Next bit explains.
Take the time to thin down the width of screwdriver blade to same as slot length, ie, make a special one for the purpose and drill out the socket midway hole a bit so the rubber hose and hole are the same size as the driver blade width. Just a sliding clearance is all that is required. Also shorten the blade so the blade thickness mates neatly into the slot to full depth with NO angular twist clearance at all. the last bit of the blade should be carefully filed parallel and not tapered as is the norm. That makes the screwdriver not want to jump out when holding and tightening the locknut. That makes the adjusting far better to feel and control the adjusting process.
I have done mine twice, or in Yankee speak, two times. Initially I purchased a new cam cover gasket but really it isn't required. I use Loctite 556 plastic gasket smeared on the parting faces and especially where the cam divet plugs are to reseal when replacing. Second time I resued the gasket which wa still in the cpver groove. Just sealed the bottom edge to head surfaces.

I have carefully washed and blown dry, the injector seal rim of each one to remove grit and dirt before the cover removal. Make sure each inj seal is perfectly clean upon removal of cover and ensure the diameter of the injector sealing surface is also clean and oiled before replacement. I haven't replaced the inj cam cover seals at all. They are undamaged and seal again.

Not sure if the pan gasket is there or not, haven't looked at one, but I would again use the Loctite plastic gasket sealant on both cleaned and dry surfaces. It won't leak.
I used to rebuild autotrans and often just used Loctite Plastic gasket to seal auto pans. Had no leak problems at all. Once tightened there is no loosening of bolts due to gasket compression over time.

As far as I know the 2012 engines and onward, had different spec inj and nozzles to the pre 2012 ones and with revised ECU programme. All have a variable turbo, that is what the vacuum chamber on top of the turbo does, it alters the exhaust ring inside the turbo exhaust housing to control boost onset and control of it too.


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PostPosted: Tue Nov 06, 2018 5:45 pm 
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Joined: Mon Nov 05, 2018 6:22 am
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thanks mydmax, i appreciate your advice
ill spend the time making the adjusting tool and screwdriver self centre smicko. the money i save will pay for my time.

im doing the adjustment myself because ive given up on mechanics who wont do it for my money or take my money and dont service it properly. seems a competent and honest mechanic is rarer than hens teeth these days. i simply can not find one that i trust to service it according to the log book. even when paying top dollar. my dmax is just out of warranty now anyway so ill make sure it gets serviced properly myself from now on. you only need a stamped log book for warranty or resale. warranty is finished and i aint ever selling it.

i thought i should change the upper seals at the same time as doing valve clearance because im getting some oil vapour leak especially around the injector seals, ive just taken the mann provent 200 off and put the original dump hose back on then cleaned the whole rocker cover. no more leaks yet but its only been a week. what are your thoughts? the provent isnt blocked up i tested it , still more constrictive than the original pipe straight into the turbo though.

was it you mydmax that suggested putting aisin manual locking hubs on? thanks i did it as you suggested and they work great, gives me low 2 as well, makes total sense not spinning the front all the time for nothing. second hand they were $200 i think, still half the price of new aisin, thanks again:)


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PostPosted: Tue Nov 06, 2018 7:30 pm 
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Joined: Sat Oct 12, 2013 5:36 pm
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4jj1
While doing the adjustment I find my modified Stanley screwdriver doesn't have sufficient handle diameter to enable a very secure grip to prevent slight turning of the screw as the locknut is tightened.
I am going to make it bigger dia to make it easier on my hand.

I know what you mean regarding service paid for but not received, I am sure it happens more than most realize. I have a number of methods for detecting such actions. It doesn't take much effort to catch them out, wish fishing was as easy. I recently bought a second hand Corolla and didn't bother to look at the service book as I know it means bugger all. At a glance I could see the engine valves had not been done even though it was past it's check distance.

If the provent has a filter it probably accumulates some oil into it and that causes a restirction and resulting pressure in the crankcase from blowby gas. The inj seals also have to suffer the pulses of pressure. Might cause a leak. That can only be wearing the rear main seal and front timing crankshaft seal by causing more lip pressure than designed.

Not sure if I mentioned to you about FWH, others may have also done it. Mine being manual the low 2wd is good for caravan and trailer reversing etc. A lot of new makes don't have wheels which allow hubs to be even attempted, no centre hole of any size in them to clear a FWH unit.

PS. When you take the hoses off the injector bleeds, carefully hold the plastic 'T' and push the hose by using a screwdriver at the edge of the hose, ie, pushing away from "T". That way the hose swells slightly and enables easy removal. Pulling on the hose only makes it grip tighter and tighter and the "T" may break.
Hope all goes well for the job.
Cheers


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PostPosted: Sat Nov 10, 2018 6:08 pm 
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Joined: Mon Nov 05, 2018 6:22 am
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all done , no probs.

cut the handle off my valve adjusting screwdriver and welded a t on top. makes it fit under the sloping firewall when doing number 4, and helps hold it better when tightening the locking nut. i grinded the point of the screw driver so it fits with no slop. didnt fill the socket and drill it out yet but i think you're right mydmax it needs doing. instead of epoxy or polyester resin i might try drilling the socket out to 12mm if possible then weld a piece of 12mm rod in there then drill it out to suit diameter of screwdriver shaft.

the job took me a while but i didnt rush it the first time, im sure i could do it in half the time next time. and look forward to it.

i couldnt find that loctite 556, did you mean 565? , any way got a tube of threebond for $11 so just used that around the cam plugs, and no leaky.

i will gerny it up clean when its stone cold then see if i get any more vapour leaks, shame about the provent filter it looked factory the way id done it and it kept heaps of oil out of the intake system. hopefully ditching the provent will keep my crankcase pressure down enough to stop any more vapour leaks. might use the bracket i made for the provent on the firewall for a fuel prefilter instead since its right next to the factory fuel filter.

by the way the parts bloke couldnt find an oil pan gasket on his parts list, i think its just threebond or silmilar, ill do this job next, then my next project is to replace the 2mm bash plates under the bull bar with some 3mm i found, then extend the bash plates past the transfer case.


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PostPosted: Sun Nov 11, 2018 5:05 am 
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Joined: Sat Oct 12, 2013 5:36 pm
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4jj1
Good job. Great to hear all went well, certainly makes it easier for next time. Maybe I got my Loctite number out of whack.

EDIT

LOCTITE 518 it is.


Last edited by mydmax on Sun Nov 11, 2018 1:39 pm, edited 1 time in total.

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PostPosted: Sun Nov 11, 2018 9:15 am 
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Joined: Sat Oct 19, 2013 10:23 pm
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Location: Darwin... sort of.
The Provent has a built in valve that prevents it over pressurising the crankcase, there are literally millions of these in service all around the world with no problems including a long list of Dmax's so it's unlikely yours would be any different. All motors weep oil as they age and having seen first hand on a number of vehicles what letting that oil through does I would make sure at the very least you have the EGR blocked.

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PostPosted: Tue Nov 13, 2018 10:46 am 
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Joined: Mon Nov 05, 2018 6:22 am
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thanks danno yeah i know the provent has an over presure valve built into the lid an another type of valve at the outlet. my injector seals and crankcase gasket started leaking a little oil vapour around the time i installed my genuine provent , after 20k its got steadily worse and started blowing off the pressure valve around the provent lid. until i recently removed it. any filter no matter how good is going to more restrictive than the 20 cm long factory pipe straight into the turbo, thus at least slightly increasing crankcase pressure.
not sure at this stage what my next move is


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PostPosted: Tue Nov 13, 2018 10:55 am 
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Joined: Mon Nov 05, 2018 6:22 am
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i ditched my plastic engine cover 20k ago when i installed the provent so its easy for me to see any vapour leaks as they happen.
i dont want to replace an $80 filter every 20k when vapour starts blowing out the lid, need a different plan. maybe a stainless reusable one , less efficient but prob also less restrictive. now that its not leaking at all, i might clean the filter and reinstall the provent and watch for leaks.
mydmax said in an old thread about cleaning a factory oil filter , is that one under four screws on the rocker cover? any info on that process would be helpful.


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PostPosted: Tue Nov 13, 2018 11:38 am 
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Joined: Sat Oct 12, 2013 5:36 pm
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4jj1
I agree with Danno that the Provent should easily vent to the exit hose via the valve if internal pressure increases too much. That just means less oil catching in the blowby stream.

What are the internal sizes of all the fittings and hoses you have used? There must be some issue with a part of the system. ie slightly kinked hose perhaps but unseen. I am not a fan of actual screen type filtered items because the filters when oiled have to pass the flow. Not sure if that is the problem though but most seem to work ok.
If the exit screen in the cam cover was at fault it would still be the fault with or without a catch can installed.
What oil you use will have a bearing on how well the rings are sealed and therefore the total amount of blowby exiting the crankcase to be passed through to the turbo inlet hose. Some oils are not good performers in sealing rings and a higher than normal blowby flow as a result. Some oils aerate more too and that means more oil in the mist.
Even so, the rate of exiting gas/mist shouldn't be causing a buildup of crankcase pressure, unless there is a dynamic flow restriction down the line. That appears to be your problem somewhere.


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