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The 520!


sycloned916

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  • 2 weeks later...

So last week I've been having some Idle Issues,so yesterday I take my truck out for a light run by Dave's shop and I pull over behind a shop and turn it off. I take some pic's and start it back up to head home and it starts to sound like it's running on 3 cylinders. I limp it home and pull the plugs and #4 is loaded with oil. So the nightmare began of pulling the head off. It's been running like shit for about a week and a half going full lean at idle and loping pretty good,I think the valve seals or guides were the cause of it all. Now it's time to rebuild it,getting all new seals with brass guides and a cometic head gasket and so here is how it sits now.

 

SR-2.jpg

 

I'm doing some port matching to the Intake and Exhaust will get polished. This is the first pass I was getting tried.

 

SR-1.jpg

SR-7.jpg

SR-6.jpg

SR-5.jpg

 

Also found this at #4 Intake.

 

SR-3.jpg

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i dont understand how the intake had oil in it when the runners all slope downward, that just doesn't make since.. the only thing i can think of that would let oil into the intake would be the pcv valve was fudged up, esp with a broken rocker arm keeping the valve closed making any sort of reversion impossible..

 

oh wait.. thats it.. the rocker broke and it kept the valves closed letting them keep in the oil from the pcv.. well either that or your turbos fucked up, an iirc its an ebay style turbo which are notorious for blowing seals an sending oil through the system.. did the intercooler or piping have any oil in it? if not then i'd assume its the pcv system.

 

so on to why the rocker broke, either you over revved or it broke because the valve couldn't open which takes us back to the oil problem, now either the oil from the pcv was able to pool up on the piston while the engine was off then you tried to start it an it broke the rocker arm Or the oil came from somewhere else, possibly the valve seals like you mentioned but thats a very uncommon sr20 problem imo. but its totally possible.

 

back on to the pcv, any chance your boosting the crankcase? this would cause pcv problems for sure.

 

anyways theres some food for thought, hope it helps.

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Does the PCV even work when your boosting an engine? Don't you have to have vacuum for it to even work? With a pressurized intake I seriously doubt it even functions, as it is just a controlled one way vacuum leak. But if the crank case was pressurized, can it force air into a boosted intake manifold, seems like there would be more pressure in the intake manifold and that would force the PCV closed. And if the block was pressurized, it would probably blow the oilpan, and valve cover gaskets anyway to releave the pressure. I am always thinking/curious, one day it will probably kill me. :lol:

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lol these motors do have pcv man. im sure they close underboost, but while just crusing even boosted engines act as n/a, the only time you really see "boost" is under acceleration an depending on the setup sometimes you dont even see full boost till 3500-4000 rpm. So while idling and crusing the pcv would work just as normal.

 

and if he was boosting the head/crank case it would blow that pcv wide open an blow oil into the intake, seen it a dozen times.

 

 

infact heres a pic of his setup, looks like a different vc but same shit..

 

004.jpg

 

the thing the blue hose connects to on the left rear of the vc is the pcv, But having that filter on the breather on the other side would make it pretty difficult to pressurize the head/crank case.

 

so if thats the case the only thing left that could be blowing oil into the intake is his turbo, but i dont see how it could build up That much oil esp while the engines off.. it would only really do it under boost..

 

 

 

OH btw man you should seriously reconsider using that cometic gasket, i've read alot of bad things about them :( look into the sr20vet headgasket thats what alot of guys are using now days. you can find one on www.gspec.com in the vvl section

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For the pass 2 weeks I've been trying to find the Idle issue i've been having. I did a pressure test and air was going into the valve cover. I have a one way valve from a Q45 on the pvc side but even with it not on the intake air was still leaking, I think through the valve seals/guides. But the oil was coming from the head,the runners were dry when I took it apart,that or the head gasket gave out. Everything else is fine.

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that tells me that the oil on the valves had to have gotten in through the intake manifold, now since the intake doesn't have oil running through it, it could have only gotten in 2 ways, either through the pcv or through the throttle body.

 

Funny that the pcv looks like it connects near #4 cylinder?

 

did all the intake ports have oil in them or just #4?

 

did all the pistons have oil on them or just #4?

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lol these motors do have pcv man. im sure they close underboost, but while just crusing even boosted engines act as n/a, the only time you really see "boost" is under acceleration an depending on the setup sometimes you dont even see full boost till 3500-4000 rpm. So while idling and crusing the pcv would work just as normal.

 

and if he was boosting the head/crank case it would blow that pcv wide open an blow oil into the intake, seen it a dozen times.

 

 

infact heres a pic of his setup, looks like a different vc but same shit..

 

004.jpg

 

the thing the blue hose connects to on the left rear of the vc is the pcv, But having that filter on the breather on the other side would make it pretty difficult to pressurize the head/crank case.

 

so if thats the case the only thing left that could be blowing oil into the intake is his turbo, but i dont see how it could build up That much oil esp while the engines off.. it would only really do it under boost..

 

 

 

OH btw man you should seriously reconsider using that cometic gasket, i've read alot of bad things about them :( look into the sr20vet headgasket thats what alot of guys are using now days. you can find one on www.gspec.com in the vvl section

 

 

I had the one-way valve just under the fuel rail on the pvc side. Thats why I think it was being sucked thru the valve seals. I'll check out that gasket thanks.

http://gspec.com/p-5003-vvl-metal-head-gasket.aspx

This one will work?

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yea i love that site, plus i think he's pretty local to you.. def a good SR guy to know.

 

he can get ANY factory nissan part as long as its still made or at least in stock somewhere in the world. i have parts on my car str8 up from japan that i had to wait a month on lol but i got it!!

 

plus if he cant get factory shit he usually has a good aftermarket source.

 

might look into gettin the valve seals from him to?

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  • 2 weeks later...

My buddy got me some 280z louvers for my 520, putting them on my first truck they looked good so I will be doing it again. I'm not sure what hood to put them on,I would like to put them on the CF hood once it's done if ever or on the metal one. There primed and ready to install.

Datsun520-1.jpg

Datsun520-2.jpg

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