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Funny Sound From My Cylinder Head

MJTru

By MJTru,
in Engines & Forced Induction

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MJTru Mentor

MJTru

Posted
Posted (edited)

I have a funny sound from my rb25det head, the sound isn't a hard sound it's just not as quite as I think it should be, I'm comparing to my friends stock rb25det. Being a mechanic I feel deeply that's it's the hydraulic lifters, When I build the block with forge pistons 9.5 to 1 compression rods, main studs N1 oil pump ACL race bearings, but the only thing I did to the head was grind the valves and replace the valve seals, I used head studs, and a multi layer head gasket. Now the head is completely stock. I reused the hydraulic lifters.

I was told that on these heads you can't grind the vales to seat them, I was told that you must slap seat them not grind then, if you are going to reuse the lifters. I have no idea what slap seating a valve is all about. Has anyone heard of this? I started thinking maybe because when you grind the valve you move it further up in the head, and the old lifters were set to the height of the last stock height. Well this is one reason why I think my lifters may be making this noise. It sounds like its slapping just a small amount. The car doesn't miss idles great, and makes a lot of power and torque, just to give an idea, the shit rips the tires loose in 4th gear, I would like to replace the lifters with new ones and see what happens, I just don't know where to buy some from.

I ran this motor hard, I did some 9000 rpm pulls a couple of times, and after reading some forms on SAU, I realized that that's not safe so I dropped it back to 7500 rpm's. To tell you the truth I'm surprised that it runs so great for so long. The motor had 50,000 km when I rebuilt it. I run 25 psi most of the time. Does anyone knows or heard of anything like this before? What do you all think I should do?

Edited by MJTru
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Hanaldo Grand Master

Hanaldo

Posted
Posted

Did you machine the head when you got the work done? I have seen an engine that was built recently, the builder machined the head and removed 10thou without realizing that the head had already been machined before. Caused piston 5 and 6 to slap against the head, sounded exactly like a noisy lifter.

MJTru Mentor

MJTru

Posted
  • Author
Posted
Did you machine the head when you got the work done? I have seen an engine that was built recently, the builder machined the head and removed 10thou without realizing that the head had already been machined before. Caused piston 5 and 6 to slap against the head, sounded exactly like a noisy lifter.

I decked the head, but the car came stock from japan, it was even an auto, But no, i didn't take anything close to 10thou off, and i really dont think thats it. The machinist just made shore that the head was flat. And even if it was hitting the head, i would guess that it would beat itself to death, and loose power? Just the other day at work i had the same problem on a mercedes engine on a Terburg truck, and from what i heard, my engine sounds nothing like it. I don't know if slaping is the right word to use, but I dont know if you ever heard and old honda engine that never had its rocker arms adjusteded, that's what it sound like.

Where can i get some new hydraulic lifter from? anyone.

t_revz Grand Master

t_revz

Posted
Posted

have seen aftermarket sets before for 700ish but cant remember where... dont bother with nissan. but its not that hard to strip and clean them. all of mine had sludge within that just needed cleaning out. let me know if you want a D&A and i will dig up the one i used

MJTru Mentor

MJTru

Posted
  • Author
Posted (edited)

thinking back on the rebuild. I had mixed up the lifters, would this cause them to make this kind of noise.

Does anyone know where i can get new lifters from, and if any of you can get me the OEM part number, i would be very thankfull.

Edited by MJTru
MJTru Mentor

MJTru

Posted
  • Author
Posted (edited)
have seen aftermarket sets before for 700ish but cant remember where... dont bother with nissan. but its not that hard to strip and clean them. all of mine had sludge within that just needed cleaning out. let me know if you want a D&A and i will dig up the one i used

please mate i bow to you, lol, D&A D&A

thanks. :D

Edited by MJTru
t_revz Grand Master

t_revz

Posted
Posted
please mate i bow to you, lol, D&A D&A

thanks. :)

http://www.gtrpwr.com/showthread.php?p=12050

this was the D&A i used but the first step of breaking em part didnt work for me(actually cracked2). instead of hitting em on the head i held them in my hand and squared them up to an anvil and gave them a quick slap and they popped straight up.

then instead of mixing all the parts up in a basket i used a fishing tackle box and filled that up once they were stripped.

post-24655-1288612983_thumb.jpg

MJTru Mentor

MJTru

Posted
  • Author
Posted (edited)

Hi there mate

in the event that anyone wants to buy lifters for there rb25det, the link has them for 408 dollars for a set of 24

FYI the lifters are the same as a 300zx twin turbo Z32 model. 1990-1996. Hope this helps anyone thats in my situation. the part number is LIFD27 by Topline

:P:laugh:

http://www.importperformanceparts.net/

Edited by MJTru

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