Rod Knock - Go JDM 7M or Overhaul Current 7M?

What To Do About Rod Knock Engine

  • Total voters
    32
ChadMKIII

ChadMKIII

Yup, Thats The G/F
Jul 14, 2006
369
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I had the head gasket replaced not long ago. Replaced with OEM HG & ARP bolts at 76 ftlbs. Only mod is a MBC from Dr. Jonez, which I'm guessing is hitting around 10 psi.

Anyway, the headgasket was replaced at 120,929 miles, with OEM bolts at 60ftlb.
At 121,865 the bolts were swapped out using the proper pattern and replaced with the ARP's mentioned above. The MBC was also added here and oil was changed again.

Ever since I got it back, I have heard a faint ticking noise, which every once in a while would be a louder rattle, but only above 2500 RPM at like 40-60% throttle. I didn't think it was a big deal at the time, just a small problem I would fix soon. A couple nights ago it suddenly became very pronounced and loud at all RPM's, and I stop driving it as soon as it became loud. Thats when it hit me: Rod Knock. Had the car towed back to the mechanic, thats what he said too. The car has 122,6xx mi. That's less than 1000 miles after the bolts and oil and everything.

There was oil on the dipstick, so I don't think it just ran out of oil, but I have no idea what the pressure was because the mechanic couldn't get it to work again after the HG. I'm also dealing with that ATM, with other shops.

So, here's my dilemna, I'm short on cash, just paid 2400 for the HG job, its going to be at least another 2000 labor, plus parts, to fix this. The mechanic doesn't look like he's going to take care of it, although I kinda think he might've had something to do with it. I never noticed the noise before, but did immediately after.

1. Does it look like the mechanic's fault?
2. What are my chances of problems with low-mile JDM engines, and what is a good place to look for them?
3. Would it be better to just rebuild mine?
4. Should I just try to sell and get a new Supra? What could I get out of it with rod knock, with everything else in pretty good condition?

TIA.

EDIT: PLEASE ALSO VOTE IN THE POLL AS WELL AS POSTING IF YOU HAVE AN OPINION SO I CAN GET A GOOD, EASY IDEA OF THE FEELINGS ON HERE. THANKS! :)

OH YEAH - I'm not even considering JZ. But thanks.
 
Last edited:
tig321

tig321

New Member
Mar 13, 2006
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I voted before I "rebuild you current engine" before I read your thread. If you don't have another car for a daily driver, and are strapped for cash, you might be a little better off in the short run buying a JDM motor. Just be sure to plastigage your bearings and retorque the head at the minimum. Then you can rebuild your current engine with forged components In your spare time.

That was my original plan, until I got my engine that is. My JDM 7M looked pretty good at first, until I noticed some intake valves were stuck open. When I removed the head to fix this and add a MHG but I found some big cracks in the block. Not suprisingly, I got the shaft on that one.

I also remember hearing something about a company that sold rebuilt jdm long blocks, I think? I can't remember the name, sorry. That might be another option though.
 
ChadMKIII

ChadMKIII

Yup, Thats The G/F
Jul 14, 2006
369
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Bay Area, Ca
Well, I was looking at getting a cheap DD so I could rebuild it personally (it would take me at least 6 months tho, most likely longer), but at this rate it doesn't look like I can afford anything I would be willing to drive (yes, I'm picky lol).

I could actually prolly borrow my grandpa's 87 Mitsubishi pick-up like I did during the BHG, but I can't stand driving it for longer than a week or so. I HATE that truck lol.

So if I were to rebuild it I'd have a shop do it, unless I can swing the price pf a temp DD (I just found a 97 Caddy Catera, under 100k mi w/ new tranny, great cond all around for 3 grand. If I can get parents to swing that I think I'll rebuild it myself)
 
canadianbacon

canadianbacon

Extra Crispy
Dec 10, 2005
226
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55
Coquitlam, BC
Nice looking car! That sucks, however rebuild your original 7M. There are no guarentees on any engine wether it is a JDM or a rebuild, unless you have someone that knows what they are doing.
It is unfortunate that the bottom end crapped out on you after your HG.
The mechanic should have done a compression test before the HG, to determine if your bottom end was in good shape, and pull the pan off to look at any wear and tear.
Had this happen to my 87.
I was in a rush to get the car going again and should have rebuilt the whole thing!
Since then, sold that car and started fresh... 9 Supras later...
Hopefully you will have it ready for spring.:icon_razz LOL
 
GrimJack

GrimJack

Administrator
Dec 31, 1969
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idriders.com
A rebuild job on your current 7M should net you a better engine than the JDM version.

However, the JDM swap will be cheaper.

I doubt this is the mechanic's fault, it's probably related to the earlier BHG - if you get water in your oil from that, it's pretty easy to roast a bearing.
 
Mr.PFloyd

Mr.PFloyd

I am the Super Devil
Jun 22, 2005
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GrimJack said:
A rebuild job on your current 7M should net you a better engine than the JDM version.

However, the JDM swap will be cheaper.

I doubt this is the mechanic's fault, it's probably related to the earlier BHG - if you get water in your oil from that, it's pretty easy to roast a bearing.
Click to expand...
thats exactly what i was thinking.
 
ChadMKIII

ChadMKIII

Yup, Thats The G/F
Jul 14, 2006
369
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Bay Area, Ca
GrimJack said:
A rebuild job on your current 7M should net you a better engine than the JDM version.

However, the JDM swap will be cheaper.

I doubt this is the mechanic's fault, it's probably related to the earlier BHG - if you get water in your oil from that, it's pretty easy to roast a bearing.
Click to expand...

Thanks, thats what I kinda thought on the engine: I would have a much better chance of having a good reliable engine if I rebuilt this one. My grandpa says that a low-mileage JDM engine should be fine, that even if it was driven hard there's not a whole lot that coulda gone wrong in, say, 30k~ish miles. But I'm nervous about buying an engine I have no history on.

What would a good price be for a JDM 7M-GTE with less than 40k?

I'm leaning towards rebuild, but I absolutely hate the idea of all this extra downtime...

So, GJ, you think that the prev BHG had something to do with this more than the mechanic? I don't get it, if I never heard any sign of the noise at all, and suddenly did after I got the car back, and the oil was completely flushed on the BHG (obviously) and again at about 900 miles, why should that've caused it? Not being confrontational, seriously asking. It just doesn't add up to me.... (Not that it should, I'm still just a noob trying to learn. Please enlighten me :))
 
M

mkIIIman089

Supramania Contributor
Mar 30, 2005
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Ohio
There doesn't have to be "all that extra down time" if you just get it done instead of starting before you have all the money you need to finish. At least, thats the most common reason they all take so long.
 
ChadMKIII

ChadMKIII

Yup, Thats The G/F
Jul 14, 2006
369
0
0
34
Bay Area, Ca
mkIIIman089 said:
There doesn't have to be "all that extra down time" if you just get it done instead of starting before you have all the money you need to finish. At least, thats the most common reason they all take so long.
Click to expand...
Well, first off I wouldn't even pull the motor till I get all the cash i need in-hand. But there's still the d/t of getting that cash. Then, I've never done much mechanical work, combine that with my OCD-ness and that I have to have things *perfect* and it would take me a LONG time to do. Like maybe finish mid summer.

Second, I highly doubt I'd do it myself, though, cuz I don't have another car I can use for an extended period of time (this is my DD). Depending, I may have the mechanic who did the HG do this if I can get a split on the price, since it just seems odd to already have rod knock (pending GJ's reply). If he does it, I don't expect to see it for about a month. If I can't get a price split, then I'll prolly go somewhere else, so should be done fairly fast. Iono yet.
 
ChadMKIII

ChadMKIII

Yup, Thats The G/F
Jul 14, 2006
369
0
0
34
Bay Area, Ca
STFU. Damn......$120???

Here I am looking at minimum 2 grand labor.....
I'm surprised you didn't say JZ. Lol.

K to everyone else I am still looking for more input! Thx for all the help so far.
This thread isn't completely off topic yet!
 
Nick M

Nick M

Black Rifles Matter
Sep 9, 2005
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I guess I don't understand why anybody would want to buy a used engine and then rebuild it.

It would be one thing if he had put a rod through the side of the block, but his is knocking. You don't even know what is wrong yet. Although a spun bearing is a likely cause for engine knock.

Perhaps you need a second car. One that is a year round beater.
 
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