I’m in the middle of some major engine work on my wife’s Toyota 1999 RAV4 (2WD, California emissions). The major motivation for this is the clutch and a head job. I’ve now got everything taken apart, and I cannot decide on whether or not to work on the “bottom end” (i.e. the short block). Here are the details:
The vehicle engine has 175,000 miles on it. We’re the original owners and it has been generally well maintained. No overheating, etc.
Over the past couple of years, it had gotten to the point of burning about 1 quart of oil about every 800 to 1,000 miles.
The burning oil seemed only to be coming at startup, thus strongly indicating bad valve guides and/or seals.
Sure enough, after getting the engine apart, it is clear the head needs to be done, and the exhaust valves in particular have been leaking oil.
A compression check before taking everything apart had each cylinder at 140 to 145 psi, with no meaningful increase doing the check after a squirt of oil into the cylinders. Spec for this engine is 128 min, 178 max.
There’s a lot of carbon build-up on the tops of the pistons, but I think that is clearly from age and the leaking valve seals.
The cylinder bores all seem pristine. No burn marks, gashes, scratches, etc. In fact, the original honing cross hatching is still clear.
Oil pressure seems fine.
SO … here’s my dilemma. I’d like to not have to deal with the time and expense of redoing the block, and given the strong compression and good visual inspection, it seems like the block is probably fine. However, am I just being a fool in not re-ringing and replacing the crank and rod bearings while I have the engine this tore down? I’d be happy if I can get another 50k or more out of this block as is. Is it normal for a Toyota 3S-FE block to still be strong well past 200k miles?
If you’re going this far, I would at least Plastigauge the rod and main bearings. This will determine if the block/crank need to be machined. http://www.plastigaugeusa.com/how.html
You can get Plastigauge at any auto parts store.
My feeling is that you should not read too much into published specs about compression readings because many of them are flat wrong. A 128 is horrible, a 140 shows wear, and the rule of thumb on a good engine is 20 X the compression ratio with a little variation based on various factors.
Is the engine still in the car? If so, I would continue with your original plan…If the engine is out, then tear it down…If you are not careful, costs can get out of hand very quickly…
The engine is out of the car and on a stand in my garage. The head is out to the shop to be redone. I know at this point it isn’t that much more work to rebuild the bottom end, but for a variety of reasons it would be nice if I didn’t have to do that right now. Pretty dumb not to re-ring and new bearings now, eh?
You can leave the lower end alone but don’t cheat much on the heads. Replace all the exhaust valves and lap them so you can halfway judge the condition of the valve seats.
The vehicle is old so you can take a few chances. Oil doesn’t cost too much.
I just noticed that the engine is on a stand. Remove the pistons and clean out any gummed up oil rings. You might thank yourself later.
Just my humble opinion and others will disagree but I would not have personally attempted a rebuild or hired someone to do it. I would have just gone with a short or long block from either the factory or a good rebuilder. It is much cheaper and all of the issures are covered.
Now that you’ve done it, or maybe you could just get the short block since you are doing all the rest now. If you had that much oil consumption before, if you put heads on that have been gone over, you are going to have much higher oil consumption due to the higher compression. I just really think its a crap shoot that you’d be losing that much oil through the guides. No point doing it half way though now, but I’d really just get a short block.
I think removing and cleaning the pistons is a good idea, since the motor is out of car on motor stand. That way you’ll see if your oil use could be a bad ring. Since the pistons are out replacing the rings makes sense. At that point you can measure the rod bearings and look for wear.
Basically, at this point if you just pop the heads back on and reinstall the motor you are betting 100% on the oil use being a “head” issue. If you are wrong, then you are either going to have to live with it, or yank it out again in a few months and then tear down the motor.
Smart money is on replacing rings and bearings now, and then you are good to go for much more than 50K, more like 150K. At 175K miles something must be showing signs of wear. Looks are OK, but measurements are better at determining wear.
If you just don’t have the time, or the money for parts, then pop it back together when the heads come back and hope your bet is correct.
The pragmatic yankee side of me thinks that, unless you have reasons to suspect the lower end having issues (noises, etc), it’d be best to just repair the top end and be done with it.
The other part of me (mostly the nagging sometimes screaming Germanic “I gotta know it is right” side), does like tester’s suggestion of using plastigauge and tearing the thing apart.
How much work is it to crack the case and do the latter?
Do you like tearing engines apart and are capable of putting them back together, without having enough parts left to build another engine?
Do you have space and time to do this?
And most importantly: Do you need the car desperately?
If not, indulge your “I gotta know it is right” side.
If it was me I would get the crank reground and put in rings and a new oil pump. Or get a short block. No guess work then. Now you have a car that will last you along time at a cost way less than a good used or new.
At your mileage, I would just replace the rings and bearings with stock size units. Unless you see evidence of damage to the journals, I would not regrind the crank because you end up exposing softer metal. If the journals appear freshly polished, leave them alone.
The reason I would rering is that it has been my experience that on high mileage engines, even when there is no appreciable wear on the cylinder walls or even on the rings, the new valve job will unseat the rings and they will start burning oil.
In your case, I would not get a reman. It sounds like you have a known good block and crank with very little internal wear. You don’t know what a reman started with. I only use a reman when I know the block I have is not worth saving.
So looks like the consensus is new rings and bearings, an oil pump, and throw in the timing belt and water pump while you’re at it (if it has a belt). Of course then new serpentine belt and hoses too. Ain’t this fun spending other peoples money?
I think we are all excited to know the engine is out of the car and anything could be done to it.
This car has a lot of miles. Mine is another vote to just do necessary repairs and keep fingers crossed. It is easy to get carried away and there is no end in sight.
I really appreciate all the input. I pulled the trigger and purchased new crank and rod bearings, and piston rings today. All said and done, about $100 plus $80 for a new oil pump, so that seemed like a no brainer. Now of course, that’s assuming I can get all of that in there easily and don’t find anything else wrong! Wish me luck, and I’ll update this after this weekend on my progress.