A rod replacement is a MAJOR engine repair. You're looking at both cylinder head removal (to lift the piston/rod out from the top) and oil pan removal (to disconnect the rod from the crankshaft).

Whether you like it or not you'll get a lot of gaskets replaced in the process, driving parts cost on top of labor. They can't reuse the head gasket, nor the cam shaft seal, and likely also not the valve cover gasket (depending on how old it is) or spark plug tube seals. They need to put new gasket maker on the oil pan. You new new oil and new coolant once they reassemble. None of these are overly expensive in and by themselves but they add up, especially when you're paying shop prices for the parts. Once they pop out the piston and rod they may also find you need new piston rings and rod bearings, and may question the value in doing that for just one cylinder. I'd also expect quite a few hours of labor for disassembly and re-assembly. By the way - yes - it would be very easy for them to pop in a new timing belt once they're in there.

I'd question whether it's more cost effective to drop in another used 4A-FE instead.

Hopefully I'm just overly pessimistic. Speedy25 and DannoXYZ and others will know better than me.

 

Where was the oil leak? What did they do to fix it?

I'm wondering why they went ahead and fixed the leak if they knew a "rod was bent." They fixed the leak before even starting the engine to hear the noise?

 

That shop is scamming you!! Immediately move your car to another shop!!!

With low oil levels, you'll end up with sporadic oil-pressure drops. By time light goes off on dash it's really too late. I don't trust it, prefer to have gauges that shows actual oil-pressure and oil-temperature.

It's pretty much impossible to bend a con-rod. Most rod failures are from over-revving and snapping a rod. And you can line up pieces and it'd still be straight. What you have is rod-knock from worn-out rod-bearings. They are very simple to replace, 2-3hrs, just 30-minutes more than replacing the oil-pan gasket. However, your engine may need more work than that.

This was my car at around 220k-miles and bearings were worn out to maximum clearance. There was no detectible knock, but I did pick up subtle fluttering shake of engine in mid-range RPMs.

The 180-240k-mile range seems to be average where these engines get rod-knock, blow headgaskets or crack valves. Made worse if you've been using Fram filters with non-synthetic oil. Your best bet is an engine-swap with an engine that's in better shape than yours. Will cost $1300-2000, much less than repairing your current one (look at all the work needed mentioned in previous posts).

 

Good point regarding mis-diagnosis. It seems OP already had the oil leak fixed by the shop (To what cost? And to DrZ's point - where was the leak?). With that being addressed already shouldn't he be looking at the option of keeping his engine and simply doing the rod bearing replacements? At least that is only a matter of dropping the oil pan, no cylinder head removal needed....

 

Depending upon how much more work is needed, yeah current engine may be salvageable.

If oil-leak was from oil-pan gasket, it would be a shame to re-do it to replace rod-bearings. Depending upon severity of wear, crank and con-rods may be damaged. The crank-machining and rod re-sizing needed to repair wouldn't be worth it.

I wonder how shop determined it was bent rod? You actually have to disassemble engine to pull out the rod to measure.

 

Yeah it was pretty "interesting" of the shop to do ANY repair on that engine prior to confirming the knocking.

Out of curiosity (and off topic) based on what you learned from your engine would you do the rod bearings as preventive maintenance at a certain mileage (say 150-180k?) on these engines or would you wait until you had any symptoms? Looks to be $19 per bearing (so about $100 total) plus the FIPG for the oil pan to do the job yourself.

 

I would just do it as preventable maintenance at 200k. By the time you hear it, might be too late. I've seen SO MANY of these mechanic's specials on Craigslist with rod-knock. Well, about half/half split with headgaskets. My Honda buddy will split with me a car to flip in a weekend with blown headgasket. But no way on one with rod-knock.

 

What does the preventative maintenance of replacing rod bearings prevent? What additional damage occurs if you continue driving when the bearings are worn past spec?

 

It's a downward spiral of accelerating wear damage that occurs. The larger the bearing clearance, the lower the oil-pressure. This lowers lubrication to cams and main journals. The larger clearances also gives the rod-journals more 'slap' to cut through the oil film and scrape the bearings. At some point, bearings will be too thin to hold themselves in notches and they'll spin.

These chunks of suicidal bearing material will marr the inside of the rods and crank journals.

At this stage, you may not even hear any rod-knock, just increased fluttering vibration of the engine which may be confused with out-of-balance tyres or worn motor-mounts. However, the clue is that the frequency is higher.

Now, if you catch it at this time, crank journals will need to be re-ground to smaller diameter and polished. Rod will need re-sizing and you'll need to source undersized bearings if they even exist.

By time you hear loud knocking, the bearing is most likely all gone. The large clearance has zero oil-pressure and crank's rod-journal grinds away rod. End-cap breaks off and the crank pounds rod out side of block.

I'm afraid the OP's engine damage may be terminal. It's extremely likely that crank and rods are scored; requiring very expensive machining to repair. Best to measure rod-bearing clearances at 200k-miles to verify wear, then replace them. On my track car, I replace rod-bearings every 2-years as a precaution.

 

What about main bearings? I'd heard that replacing rod bearings alone isn't ideal because it can negatively affect worn main bearings. Any truth in that?

 

Main bearings last 3-5x longer than rod-bearing because they don't face as large radial loads. Main crank journal stays in centre of bearing and just spins instead of swinging.

 

When I took my not quite 300k engine apart a few years back, I was surprised to find the bottom end was bulletproof and there wasnt ANY wear. I had run this engine low on oil a few times because of its extreme appetite for it. To have one of these cars develop rod knock or have a bent rod is almost impossible.

Your economic answer is get a used engine and install it. You will spend $1000+ on rebuild services and parts. I did and I did it all myself. High mileage vehicles get a lot of worn out parts you dont think about until you take them apart and see how bad they really are.

Once upon a time I did get a used Kia engine that would turn hard at just one certain spot. THAT was a bent rod. I have no idea how it was done, but it happened. I swapped a rod from the destroyed engine and put it all together. Last I heard it had gotten to Utah OK, so that engine was a runner.

I also think that shop should not charge you for doing "un-necessary" repair work on an engine that was brought in with a problem.

-SP

 

When I took my not quite 300k engine apart a few years back, I was surprised to find the bottom end was bulletproof and there wasnt ANY wear. I had run this engine low on oil a few times because of its extreme appetite for it.

did you actually measure the clearances though? Up to about 80% worn, they'll look perfectly smooth and fine. Only way to gauge wear is to measure the clearance and come up with some numbers.

That said, bottom ends are very durable if maintained with quality filters and synthetic oil. You'll most likely have headgasket or valvetrain issues at end-of-life for engine.

 

That said, bottom ends are very durable if maintained with quality filters and synthetic oil. You'll most likely have headgasket or valvetrain issues at end-of-life for engine.

So rod bearing damage is a result of poor maintenance such as poor quality oil and filters, and not an expected wear item?

 

Well, it's a wide range depending upon the entire history of the car. In my case, my wife was starving student who used those $19 oil-change specials. Got no-name oil-filters with probably single-weight unknown dino oils.

By the time I came around at 150K-miles, the damage was done. One of the cylinders was down to 90psi with clogged rings from burnt oil. I manage to piston-soak and clear the cylinders out. Could see shiny silver piston tops and the cast-in numbers. Compression back up to ~190 across the board.

Even with better filters and full-synthetic oil, it only had 70K-miles left on the rod-bearings.

So yes & no, it depends upon the maintenance history. And if you don't have complete history, i'd err on the safe side and replace then. It's actually a very simple procedure, easier than water-pump or timing-belt.

 

Yes and no.

 

This has been the best thread on TN I have read today. And I read a lot of them. Thanks for the insight guys and OP I hope the shop does you right, my mechanic wouldn't do any repair until they consulted with me in that situation. I think a new shop might be the right choice. I also think perhaps pull the pan and measure as they say then look for a junkyard swap.

As an aside with mobil one oil and filter how long will an 2az go? You have me a little anxious as my 255k is only about half what I want to get before I decide on a course of action.

 

https://monkeywrenchracing.com/prod...0308/corollamatrix0308enginesheadsblocks/corollamatrix0308completebuiltengines/

 

Unfortunately we have the 4A-FE/7A-FE, not the 1ZZ-FE so we can't toss one of those in. Now if those Filipino folks would share how they managed a 2ZZ swap on Facebook, I'm sure quite a few of us would get right on that!

 

OP - time for you to let us know what the shop came back with

DannoXYZ - thanks for the advice on the rod bearings. Give we've owned our Corolla from Day 1 with consistent oil changes and she's only seen a quick lube place 3-4 times in 23 years I think we're in good shape. I might still take your advice and pop them out around 200k or if/when the oil pan gasket starts leaking, whichever occurs first Sounds like a good "add-on" job for any time the oil pan has to come off.

 

Yeah I know that wasn't the correct engine but I thought they had other long blocks. I guess not