Serious issues with my RB25

[NPux]

Hi everyone,

In October 2006 I decided to buy a RB25DET from a local shop to swap into my S14. Before swapping anything in my car I decided I would change everything into the engine to make it reliable as much as possible.

I've changed every single gasket possible, I also added the JUN crank collar, put ARP rod and head studs, new Greddy timing belt, cleaned everything and put it back.

I then swapped the engine into my S14. Wiring went fine. I started it up, and this is where it all started going downhill. I immediately heard a very loud knocking that would follow the RPM. I thought it was time to get some ACL race bearings, so this is what I did. I bought ACL race rod and main bearings, so every single bearings of the engine were changed and installed properly... And then I install it back into the car, and again that damn knocking sound is still there and alive. I took the time to record a video for you all to see and hear:



Now I really don't know what's going on. When I went to a machine shop to get my JUN collar installed, the shop told me my crank was in very good shape and that the journals on it were fine.

Should I send the block to a local machine shop and rebuild it completely? I spent so much time and money into it so far and I know if I do that it will cost much more. I'm seriously out of ideas and would like to know different routes I could take before I spend much more.

Thank you

[Coolwhip]

hows your timing? hows your oil pressure?

What kind of oil are you using

[NPux]

My oil pressure is in specs (I got a Automoter pressure gauge, it sits between 50-65 psi at idle), I use mineral 10w-30 oil.

My timing is stock.

[Coolwhip]

its hard to tell where the noise is coming from in the vid. Perhaps collapesed lifter(s)?

[NPux]

The sound is much more audible near the block. It's easier to hear the knocking when I'm near the oil pan, and when I put my hand on it, it's easy to feel the knocking with the vibrations.

[minivan_don]

My oil pressure is in specs (I got a Automoter pressure gauge, it sits between 50-65 psi at idle), I use mineral 10w-30 oil.

My timing is stock.

is that at cold ?? thats damn near impossible when warm at idel...

what are the bearing clearances ?

[minivan_don]

also it sound like your timing belt is a bit too tight...

[Carl H]

or the timing belt is too loose...

[Shocker]

eww.. definitally some metal to metal contact... like valve train hitting something....

[Darius]

wow. I thought my ticking was loud when my lifters were too short. That sounds like there arne't even lifters in it .

First, double check your timing belt and that the marks all still line up with the timing cover notches.

Then, I would pull the spark plugs and stick one of those magnets on the telescoping stick down in there and see if you pull up any shards. Could be like Shocker and have a bolt bouncing around in there. Do not turn that thing over until you figure this out. At this point, you could take the block apart and have it machined for about $500 (deck and hone cylinders) assuming the cylinders are still in tact. You already spent some good money on bearings and fasteners. When you were in the bottom end, you didn't replace the rod or main fasteners did you?

[Shocker]

yeah, try a magnent in the spark plug holes, problem I had with that was the damage was under my quench wells so it was harder to get it in there. Thus head had to be removed.

[rotorimp]

When you put the new bearings what were your clearances? I build all my motors to the .0000--it is important!

[NPux]

All my timing marks are aligned.

The things I've changed on the bottom end are the rod studs - I changed them with ARP rod studs. I've also changed all the bearings with ACL race bearings. I didn't change the bolts that hold the main cap on the crank, maybe that could be the problem?

Today I took the engine off the car again *sigh*. I also took off some bearings, and I've taken pictures of them for you to see:

[Coolwhip]

main #4 looks scary...

buy some plasti-gauge and check clearances as well.

(Just for my own well-being what size bearings did you buy/use.. Were there any bad conditions to your crank before hand?)

[NPux]

I bought the ACL bearings from CompulsiveHP, STD size (didn't get oversized ones). I'll get a plasti-gauge to see what's going on, thx for the suggestion.

No, there weren't any damages to my crank... The journals always looked fine... I agree with you that the main #4 has had some damage to it for some reasons.

[Darius]

Wow your bearings are all smoked! What the heck happened to them? Did you use plenty of assembly lube for startup? Does your oil pump work? Do you still have your old bearings to measure their thickness? Was there any significance to showing a pic of rod cap #6 (like it was loose) or was it just for an example?

[gawdzilla]

from the main bearing pics it looks like your main clearances are loose and the crank is slapping the bearings there?

did you change your fasteners? you're not supposed to re-use oem rod/main bolts, especially rod bolts. they stretch beyond spec fast.

if you changed the fasteners you needed to get all your big ends checked again for roundness.

did you just throw the motor back together without mic'ing the oil clearances?

[Darius]

I'm assuming that since he didn't pull the pistons, that the rod fasteners are still the stockers. That's another good point, they are notorious for not being reusable.

[240z4u]

Hey guys, after re-reading the first post i see that this was a problem with old bearings installed as well.

What did they look like? Seems to me like your oil pump never primed itself and you had no oil pressure. I packed mine with assembly lube before putting it back on.

Just listened to your video, what the hell were you thinking letting your motor run like that for so long making that noise!?!?! Thats horrendous!

Evan

[NPux]

The video taken was with my OEM bearings, not with the ACL. When I started it up with the ACL and found out it was making that same noise, I turned it off immediately.

I didn't use stock fasteners for the rods, I got ARPs as you can see in the picture. The picture of the rod #6 was just an example.

As for the oil pump issue... I have a oil pressure gauge. I disconnected the pump gas and turned the engine with the starter till I had oil pressure (took 10 seconds). Did that for about 2-3 mins and then I started it up.

I did put a lot of Clevite lube on all the bearings.

I still have my old OEM bearings, I'll take pictures of them right now and post it here.

I totally agree with you all about the look of the ACL bearings... it looks like there was no oil. This is really strange cause I did have oil pressure.
Modified by NPux at 3:18 PM 7/27/2007

[turbocrisper]

it looks like there is no thrust bearing installed in the engine in the pic of the rotating assy i would check endplay see id the counterweights are hitting the inside the block

[NPux]

it looks like there is no thrust bearing installed in the engine in the pic of the rotating assy i would check endplay see id the counterweights are hitting the inside the block

I thought the bearing #4 (main bearing) was the thrust bearing?

Here I've taken a pic of where it's hard to see on the other pics:


Modified by NPux at 4:42 PM 7/27/2007

[gawdzilla]

so it was knocking before and all you did was change bearings and fasteners?

I'm not surprised its still knocking. In fact its probably expected. How did the machine shop check your crank and know it "was in very good shape"?

something had to be loose in order to make that knocking, and that knocking probably made some mains/rods/crank out of round on the OEM setup. By throwing new bearings and fasteners in, your mains/rods/crank could still be off. On top of that, by changing the bearings (just some generic standard size), your oil clearances are probably thrown off some more. Finally, by changing fasteners to ARP you introduced another variable which is the roundness of your hardware AFTER the ARP fasteners are properly torqued.

With these 3 combined i'd almost expect the motor to knock just as bad or worse as before... seems like you need to do a full teardown.

[eh?]

Was there visable damage to any of the bearings, rods, or crank?

A bad throwout bearing can and does make a clanking sound that will resemble a spun bearing. The sound will obviously follow RPM and it will sound like a bearing in #4,#5 or #6 has spun.

[rotorimp]

+1 for checking the thrust clearance--looks like it got pretty hot! Since you havn't posted anything about clearances--I'm pretty sure that is your problem!!.

[NPux]

I am getting plasti-gauge today and will let you know.

No visual damages to anything besides the stock bearings when I took them out.

[NPux]

Was there visable damage to any of the bearings, rods, or crank?

A bad throwout bearing can and does make a clanking sound that will resemble a spun bearing. The sound will obviously follow RPM and it will sound like a bearing in #4,#5 or #6 has spun.

Exactly like you're saying, it was easier to hear the clanking sound near cylinder #5 and #6, I'd put my hand on the oil pan and vibrations were there.

I'll get a feeler gauge and check the thrust clearance, but let's say that's the problem, what can be the solution to fix that considering my thrust bearing (bearing #4) is new? I'd need to get a oversized one?

[rotorimp]

Yes and have the crank ground IF that is the problem. Also make sure that the flywheel/clutch was not doing anything weird. Look at he wrist pins and make sure it is not on the piston side of the rod.