Just replace rod bearings and go ?

[thevork]

Hi guys, I'm looking for some advice on my 7M engine.

I overhauled the engine 30.000kms ago. All new seals, bearings, head gasked. The whole shebang. She ran like a dream up until recently.
After placing a 62-2 trim turbo it didn't took the nr 4 rod bearing a long time to die on me. I know that it's the nr 4 because when I pull the Nr.4 spark plug wire the knocking stops.

Knocking is fairly light. It just sometimes occurs, not all the time and I did not drive one mile since I have this problem (only idling), so I think (or: hope) there is no or almost no damage to the crank.

Mods include a 550cc/lexus v8 combo, upgraded spark plug wires, extra oil cooler, wideband, avc-r, s-afc, hks turbo timer, upgraded fuel system, Titan HG, ARP bolts, upgraded exhaust mani, upgraded clutch etc etc. Rebuilt 7m head.

So actually almost everything in or on the engine is brand new or almost brand new.
I was pushing 360hp and 600nm of torque with my 57 trim turbo, and much much more with the new 62 trim ct26.
My guess is the stock oil supply was not good enough for this amount of power.


I'm looking for a way to get my engine back up and running again and keep the cost down (I already invested a lot over the past years), to just be able to use the car (not race it), and sell the 7M to fund a 2JZ swap.

Now you guys know al this info, maybe you can shed some light to my question.

I want to take out the engine and just remove the crankshaft and replace the rod bearings (and maybe even the main bearing while i'm at it) but I do not want to take the head off again.

Can I take the engine out, remove the crankshaft , get it polished and put some (upgraded?) rod bearings in ?
Or is it an almost impossible task?
And if I replace the bearings, will the engine be good to go, even when pushed hard? or should I sell it and tell the new owner to run no more than stock boost?


Thanks for looking and your replies.

 

[IanC]

Only way to know for sure is popping the oil pan off and inspecting the crank, rods and caps. If you caught it early enough you may be able to replace the bearings and be good.

 

[thevork]

I will inspect everything, and eventually replace parts if needed.
I just want to have information about whether

- I can replace the bearings without taking the whole engine apart ?
- If the above answer is yes, can I get the bearings on a level where I can use my current setup and push it hard, or should I replace the engine (2jz) and in the meantime drive like a grandma?
- What bearing to get etc etc.

Note about the 2JZ swap:
Not that my 7M is not a good engine, It's just that I'm looking for a whole new challenge. My 7M was not a bad engine. I killed it by pushing it too hard. It's my fault, not the engine's fault.
A broken 7M does about 200 euro's around here. A complete and working 7M does about 800 tot 1000 euros. And as said before I need money for a 2jz swap. But I wouldn't mind driving the supra up until a buyer for the 7M comes along...

 

[radiod]

- I can replace the bearings without taking the whole engine apart ?

It's possible, but it's a major pain. You end up having to support the engine from above, undo the mounts, and lower the frame to get the oil pan off. It's been done before when people haven't had access to an engine hoist, but in reality it's easier to pull it and work on it out of the car.

 

[Dan_Gyoba]

You cannot pull the crank without removing the lower timing cover. You cannot remove the lower timing cover with the head on.

Maybe you can replace the bearings, but only if there is zero crank damage.

 

[gaboonviper85]

You cannot pull the crank without removing the lower timing cover. You cannot remove the lower timing cover with the head on.

Maybe you can replace the bearings, but only if there is zero crank damage.

You don't need to remove the crank to put rod bearings in....but the whole idea sounds shady....it will knock again.

 

[Dan_Gyoba]

I want to take out the engine and just remove the crankshaft and replace the rod bearings (and maybe even the main bearing while i'm at it) but I do not want to take the head off again.

This is what I was replying to. that is, removing the engine from the chassis, and pulling the crankshaft without removing the head.

Engine is out of the car, so no messing around with the subframe, but actually pulling the crank from the block, which requires removal of the lower timing cover, which requires removal of the head.

Yes, you can replace the bearings only, as I said, so long as there is zero crank damage. If this is the case, why would it knock again? I would say that would only be the case if something is damaged and not repaired. If it is a case of rod knock developing after a BHG repair because the bearings got damaged by acidic residue in the oil, and you replace the bearings, it should be fine. I would worry some about the condition of the main bearings, but from the information in the first post, this seems like a reasonable repair, and one at a fairly low cost to accomplish.

I would feel better about it personally if the crank were taken out so that the main bearings could also be inspected, but that does entail removing the cylinder head.

For what it's worth, I was considering doing this on my engine. It has a rod knocking, and I just wanted it to be driveable again while I am building the new engine for it. I am still considering doing this, depending on what progress I make this winter on getting the block put together. In my case though, I don't care if it doesn't last, since the plan is to rebuild the engine from the block up when I pull it to replace it with the one on the stand now. That being said, if the crank journals look good, I'd probably leave it alone.

 

[thevork]

@dan So actually you're telling me that I should pull the engine out, inspect the bearings and if the main bearings are still OK, I can replace the rod bearings with the crank in place.
If not, then I must pull the head. (Which I will not do).

Thanks for the help!

 

[Turbo Habanero]

How do you know it's a rod bearing ?

To me to doesn't seem like the power you'd be making would cause a bearing to flatten out or go bad. First you should do is drain the oil and search thru it looking for metal shavings.

If its intermittent I'd be thinking along the lines of what just happened to me.

I have a brand new 1jz engine that has never been driven but was knocking very loudly but only sometimes.. Sounded just like rod knock. But it turned out to be a small metal sliver on top of my number one cylinder.

The noise would stop when the sliver would fall into the valve relief.

Here's a pick of the sliver and damage it caused. Believe it or not the below pics are a zero mileage motor.

 

[thevork]

Oh man that looks bad!

Yes I will drain the oil and take a look.
However, I can't see how anything could get into the engine as all clamps are on, filters in place etc etc.

Why I think it's a bearing? Because it really sounds like a bearing gone bad, and when I disconnect the nr.4 spark plug cable the knocking stops immediately.
So as soon as there's no power in that cilinder the knocking stops. If there was a rock or metal chip inside the cilinder, I guess the noise would not stop after pulling the spark plug, or would it?

It would be great if it wasn't the bearing that 's gone bad! But if it looks like a duck and quacks like a duck... :'(

thanks for all the input and help so far!

 

[7M4EVR]

Just out of curiosity, you said all new bearings were put in 30,000 km ago. When u did that did u get the crank turned, did you put new main bearings in too, and did u put the thrust washer back in right? Even if all your looking to do is put new bearings in to stop the knock long enough to sell it (which is shady) doesn't it just make sense to tear it down the right way and find the problem for sure? Otherwise your spending money and taking stabs in the dark to fix the problem. When u can fix it for cheap enough doing it right the first time. Besides, if I had already had my build done with a bigger turbo like that and those mods I wouldn't be itching to go 2j like u are. C Mon man stick it out, don't give up.

 

[thevork]

I got a professional shop do all the work on the bearings for me. They reinstalled the pistons, main and rod bearings, crankshaft etc.
So I got the shortblock back from the engine shop (which is known to be very good and they did a fair share of 7M engines) and put on the head myself and built op the rest of the engine.
So actually I got it done right, with quality aftermarket parts where needed and parts from the stealer where I couldn't find a cheaper alternative.

And yes, fixing it cheap and selling it does not only SOUND shady, it IS shady. So that's why I will only sell it with the buyer knowing everything that has ever happened to this engine. I will not withhold any information

Anyway yes I'm thinking to redo my 7M, because I already have all the performance parts I'd ever want for my 7M. I can reuse the MHG (titan, so rebadged cometic, the newer style without the rivet problem) and almost everything else is new or max 6 years old on the engine.
Pulling the engine, getting the head resurfaced and the crank redone with good bearings seems the cheapest way for me to get back on the road again.

The only reason for 2J is that I'm always cautious when pushing the 7M really hard, and a little afraid that it might just take a crap on me while on the road.
For the 7M to make the amount of power I did (400++ hp) it really needs good parts and modifications. A JZ at 400 hp just yawns a little, scratches its ass and takes short naps while pushed hard. So it would take a lot of worries away from me. (along with a good amount of cash...)

 

[Insidious Surmiser]

a little OT, but just so you know... guys do make 600+ whp on stock 7M blocks.... that said. I would thrash my 7m as often as my engine got warmed up. Respectfully of course... it NEVER broke down on ME... (12psi, stock motor, divorced downpipe, tune, ect....) generally speaking though.... a 7m should hold 500hp with ease

 

[thevork]

Kicking this topic back up as i've decided to rebuild the old 7M...again...
So at first I will need to look at what made the engine knock in the first place. The engine got all new bearing just 30k kilometres back.
The engine started to smoke badly the last few drives so maybe one of my piston rings was on its way out and caused more oil to be burned than to be used for lubrication?

Ah well. Won't know that for sure until I get the supra out of the storage.
My real next question is what bearings to get. A few years back everyone was getting the Cleavite77's, but I read somewhere that cleavite doesn't make them anymore but buys and rebadges some other brand ?
So I'll rebuild just again, and what bearing should I get? Should I be looking for upgraded bearings compared to the toyota bearings ?
I do not trust the toyota bearings as these engines always develope rod knock, and always at some point the bearings go out.

Can anyone point me in the right direction please?
I've searched on the subject, but most of the threads are rather old and as years pass materials and upgrades keep getting better and better. I'd like to know what's the best in the market today for a reliable 7m.

 

[thevork]

Nobody who can point me in the direction of good quality bearings? :'(

 

[Dan_Gyoba]

Nothing wrong with the Clevite 77 bearings at Driftmotion.

 

[thevork]

Hey Dan thank you for your answer, I appreciate it.

But the new clevites are not "real" clevite's anymore from what i've read, and I was wondering if the ones that are being sold now are much better than stock toyota bearings ?
Any thoughts on that perhaps?