Jump to content
SAU Community

Recommended Posts

Hey guys.

I just transplanted an RB25DE (with VCT) in my S. This new engine under load has a strange metallic noise around two and three thou RPM, more like two metal parts being in contact and resonating. It always occurs around 2-3K then goes away. It seems to settle down slightly when the engine reaches operating temp. The noise is the same even with VCT solenoid disconnected.

The noise appears to be coming from the exhaust, yet I removed all shields and is still there. Noise could transmit though from the engine.

The spark plugs are very clean and white, so there seems to be no valve problems. The car accelerates and idles very smoothly. Fuel consumption for this new engine seems to be higher than what it should be (although these issues may not be linked).

Any ideas to what it may be and how to fix?

Thanks in advance =]

Link to comment
https://www.sau.com.au/forums/topic/170221-rb25de-metalic-resonating/
Share on other sites

no idea what it sounds like... but if it is what i think you're trying to describe then it's a typical inline 6 twin cam characteristic... the m3 has a slight metallic raspy sound (and yes i have heard one in full song in real life) - and although not comparable, it is quite distinct.

try to put a sound file up... easier to diagnose

could be either one of ur mufflers have collapsed. or your cat. hit them to see if it rattles that or check for loose bolts or washers

Done that.. Exhaust is fine. Nothing rattles.. no loose bolts.. only thing I found once I took off the sheilding was a small rock. Muffler and cat have no noise at all.

Ill try getting a sound file :O

Im going with eugene, mine sounded terrible till i got a proper exhaust put on it, its a twin cam thing, do a search on exhausts in this section to get a better idea of muffler, resonator and pipe diameter to fix the problem. I also learned the other day, like a resonator a pipe can be added perpendicular to ur normal exhaust just to act as another expansion chamber.. honda uses this to deal with the twin cam resonance.

Unfortunately I cannot import a sound clip from my phone to my copmputer.

Is there anywhere I can hear a 25DE engine? On a video or sound clip to compair the two?

As per before.. just sounds like metal clipping.

It could be your gearbox. I ran my car with the rubber gear boot off once, and the noise was extremely loud and it was obviously coming from the gearbox. Nothing to worry about. Could see if changing your oil improves it. Check that your gear boot is fitted properly.

It could be your gearbox. I ran my car with the rubber gear boot off once, and the noise was extremely loud and it was obviously coming from the gearbox.

But why would the resonating be between 2-3 K? If it was the G-box.. wouldnt it be throughout all RMP range? And Im pretty sure its from the engine. When we opened the G-box it was in pretty good nik. It seems like its comming from the engine and all simptoms seem to point that way. Thats why Im so freaked out about it.

I have that sound too. Ill try get a sound file now.

Much appreciated brother bear!

But why would the resonating be between 2-3 K? If it was the G-box.. wouldnt it be throughout all RMP range? And Im pretty sure its from the engine. When we opened the G-box it was in pretty good nik. It seems like its comming from the engine and all simptoms seem to point that way. Thats why Im so freaked out about it.

no. it hits its natural frequency at this rpm range, hence making the noise.

I have the same noise with my r32 gts25, it has the rb25de as well and is making the metallic noise around the same rev range. I have only just started noticing it within the past 2 weeks( have had my licence for a month now lol)

my exhaust seems to be running quite hot as well, but not hot enough for the exhaust overheat light to come on.

Ill check my cat and exhaust out on the weekend anyway.

Ps i have an auto gearbox and flushed it out as well as the torque convertor and replaced with new fluid but still sounds the same.

YES!..

But without the sexual exhaust note..

Got my papa bear to drive it today.. its freakin LOUD!.. the metalic resonating is just like the one you showed.. but just much louder and somehow.. nastier sounding..

I take it by the replies that its just a normal sound?

It has a stock RB20DET exhaust with the slightly bent R33 25DE connector from the headers to the exhaust flange. Does anyone see anything wrong with this?

Much appreciated sound clip :)

What size is your exhaust GTS4WD anyway now that you did the transplant?

I transplanted a Rb25DE from a 4wd Stagea into my R32 GTS4 which had an RB20DET. It has a stock 20DET exhaust. The only difference is that I used an R33 connector pipe from a RB25DE to connect the headers to the stock RB20DET exhaust.

  • 3 weeks later...

if anyone still cares.. This metalic resonating is a common problem in early RB25DE's.. It causes absolutely no damage to the engine/exhaust.. The only way to get rid of it is a cat/exhaust/muff.. or bear they annoying very loud rattle..

Advan (in Syd) + 1 point!

The way it was explained to me is that:

"all engines make noise due to moving parts/rpm/mods etc..

Most engines sound different, they have different mechanical characteristics and that makes them sound diff..

early models of the RB25DE have that loud metalic raspy resonance due to the way the engine was designed"

Its a shit load louder than a raspy cams sound.. Got a mate to drive it the other day so i could hear it from the outside..

its LOUD! i mean FREAKING LOUD! it resonates through the whole exhaust and is amplified and expeled out the end.

In the later Rb25DE's there was a small flap that was kept closed at row rpm and opened at WOP and higher RPM to help keep the noise of it to a minimum.

An exhaust/muffler will cancel the sound, hence there arnt any/rarely do modded 25de's have the sound. Couple it with a new exhaust, and it disapears completely.

So yeah, its just a natural characteristic that 25de's have. Its similar to cams on full symphany, but a million times louder, and out the exhaust.

Theres no mechanical defect with the engine/exhaust. It causes no damage and will not harm the engine.. its just there..

hope this little bit of info helps anyone in the future..

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • OK, so again it has been a bit of a break but it was around researching what had been done since I didn't have access to Neil's records and not everything is obvious without pulling stuff apart. Happily the guy who assembled the engine had kept reasonable records, so we now know the final spec is: Bottom end: Standard block and crank Ross 86.5mm forgies, 9:1 compression Spool forged rods Standard main bolts Oil pump Spool billet gears in standard housing Aeroflow extended and baffled sump Head Freshly rebuilt standard head with new 80lb valve springs Mild porting/port match Head oil feed restrictor VCT disabled Tighe 805C reground cams (255 duration, 8.93 lift)  Adjustable cam gears on inlet/exhaust Standard head bolts, gasket not confirmed but assumed MLS External 555cc Nismo injectors Z32 AFM Bosch 023 Intank fuel pump Garret 2871 (factory housings and manifold) Hypertune FFP plenum with standard throttle   Time to book in a trip to Unigroup
    • I forgot about my shiny new plates!
    • Well, apparently they do fit, however this wont be a problem if not because the car will be stationary while i do the suspension work. I was just going to use the 16's to roll the old girl around if I needed to. I just need to get the E90 back on the road first. Yes! I'm a believer! 🙌 So, I contacted them because the site kinda sucks and I was really confused about what I'd need. They put together a package for me and because I was spraying all the seat surfaces and not doing spot fixes I decided not to send them a headrest to colour match, I just used their colour on file (and it was spot on).  I got some heavy duty cleaner, 1L of colour, a small bottle of dye hardener and a small bottle of the dye top coat. I also got a spray gun as I needed a larger nozzle than the gun I had and it was only $40 extra. From memory the total was ~$450 ish. Its not cheap but the result is awesome. They did add repair bits and pieces to the quote originally and the cost came down significantly when I said I didn't need any repair products. I did it over a weekend. The only issues I had were my own; I forgot to mix the hardener into the dye two coats but I had enough dye for 2 more coats with the hardener. I also just used up all the dye because why not and i rushed the last coat which gave me some runs. Thankfully the runs are under the headrests. The gun pattern wasn't great, very round and would have been better if it was a line. It made it a little tricky to get consistent coverage and I think having done the extra coats probably helped conceal any coverage issues. I contacted them again a few months later so I could get our X5 done (who the f**k thought white leather was a good idea for a family car?!) and they said they had some training to do in Sydney and I could get a reduced rate on the leather fix in the X5 if I let them demo their product on our car. So I agreed. When I took Bec in the E39 to pick it up, I showed them the job I'd done in my car and they were all (students included) really impressed. Note that they said the runs I created could be fixed easily at the time with a brush or an air compressor gun. So, now with the two cars done I can absolutely recommend Colourlock.  I'll take pics of both interiors and create a new thread.
    • Power is fed to the ECU when the ignition switch is switched to IGN, at terminal 58. That same wire also connects to the ECCS relay to provide both the coil power and the contact side. When the ECU sees power at 58 it switches 16 to earth, which pulls the ECCS relay on, which feeds main power into the ECU and also to a bunch of other things. None of this is directly involved in the fuel pump - it just has to happen first. The ECU will pull terminal 18 to earth when it wants the fuel pump to run. This allows the fuel pump relay to pull in, which switches power on into the rest of the fuel pump control equipment. The fuel pump control regulator is controlled from terminal 104 on the ECU and is switched high or low depending on whether the ECU thinks the pump needs to run high or low. (I don't know which way around that is, and it really doesn't matter right now). The fuel pump control reg is really just a resistor that controls how the power through the pump goes to earth. Either straight to earth, or via the resistor. This part doesn't matter much to us today. The power to the fuel pump relay comes from one of the switched wires from the IGN switch and fusebox that is not shown off to the left of this page. That power runs the fuel pump relay coil and a number of other engine peripherals. Those peripherals don't really matter. All that matters is that there should be power available at the relay when the key is in the right position. At least - I think it's switched. If it's not switched, then power will be there all the time. Either way, if you don't have power there when you need it (ie, key on) then it won't work. The input-output switching side of the relay gains its power from a line similar (but not the same as) the one that feeds the ECU. SO I presume that is switched. Again, if there is not power there when you need it, then you have to look upstream. And... the upshot of all that? There is no "ground" at the fuel pump relay. Where you say: and say that pin 1 Black/Pink is ground, that is not true. The ECU trigger is AF73, is black/pink, and is the "ground". When the ECU says it is. The Blue/White wire is the "constant" 12V to power the relay's coil. And when I say "constant", I mean it may well only be on when the key is on. As I said above. So, when the ECU says not to be running the pump (which is any time after about 3s of switching on, with no crank signal or engine speed yet), then you should see 12V at both 1 and 2. Because the 12V will be all the way up to the ECU terminal 18, waiting to be switched to ground. When the ECU switches the fuel pump on, then AF73 should go to ~0V, having been switched to ground and the voltage drop now occurring over the relay coil. 3 & 5 are easy. 5 is the other "constant" 12V, that may or may not be constant but will very much want to be there when the key is on. Same as above. 3 goes to the pump. There should never be 12V visible at 3 unless the relay is pulled in. As to where the immobiliser might have been spliced into all this.... It will either have to be on wire AF70 or AF71, whichever is most accessible near the alarm. Given that all those wires run from the engine bay fusebox or the ECU, via the driver's area to the rear of the car, it could really be either. AF70 will be the same colour from the appropriate fuse all the way to the pump. If it has been cut and is dangling, you should be able to see that  in that area somewhere. Same with AF71.   You really should be able to force the pump to run. Just jump 12V onto AF72 and it should go. That will prove that the pump itself is willing to go along with you when you sort out the upstream. You really should be able to force the fuel pump relay on. Just short AF73 to earth when the key is on. If the pump runs, then the relay is fine, and all the power up to both inputs on the relay is fine. If it doesn't run (and given that you checked the relay itself actually works) then one or both of AF70 and AF71 are not bringing power to the game.
    • @PranK can you elaborate further on the Colorlock Dye? The website has a lot of options. I'm sure you've done all the research. I have old genuine leather seats that I have bought various refurbing creams and such, but never a dye. Any info on how long it lasts? Does it wash out? Is it a hassle? What product do I actually need? Am I just buying this kit and following the steps the page advises or something else? https://www.colourlockaustralia.com.au/colourlock-leather-repair-kit-dye.html
×
×
  • Create New...