Guest tenorGJ

Need Expert Advice...

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Guest tenorGJ

Hi everyone...

The car: 98 Corolla VE, 3 speed, 81k miles

I inherited my GF's (now wife) 98 Corolla VE 3 speed and have begun fixing up the car. This past weekend I changed the air filter, plugs, changed the oil and PCV valve. I also had a 4-wheel alignment done. I finally cleaned the throttle body. The car recently had a trans flush performed. I installed 4 new Goodyear Comfortred tires set to 30 psi.

She was only averaging mid to low 20s in terms of mpg, so I'm on a mission to stretch that mpg up into the 30s.

I've increased the tire pressures to 32psi. I rarely run the air and always have the windows rolled up. I stay below 65 on the highway (NVH with the 3 speed) and accelerate conservatively.

Some noises:

I have a strange popping noise when the following occurs--I reverse out of the driveway. Then I move to drive. The first time that I apply the brakes in drive I get a loud popping noise. The noise can be reproduced at will.

The mechanic that did the alignment said he didn't see anything wrong with the suspension. With the car up on the rack and in neutral he spun the front wheels clockwise and counterclockwise. At the moment the wheel changed direction, we heard the pop. He thinks it's in the transmission.

I've also got the loud start up noise--I believe the belt tensioner needs adjusting/replacement.

Any thoughts?


The car has never gotten a check engine light, but the mileage is terrible. I know the 3 speed has a lot to do with it. I'm currently running 5W-30 with an Auto-Rx engine cleaner treatment. I've also used a bottle of Techron to clean the injectors. The throttle body was varnished but pretty clean.

There is a lot of varnish under the engine oil filler cap and on the dipstick.

I noticed oil in the PCV valve when I removed it. Is that a problem? There are no engine leaks.

What else can I do? I have the Haynes' manual and have attempted what I'm comfortable doing. I really need some expert advice from the board.


Greg in Atlanta

Have you monitored oil consumption? Sometimes it can be a problem in Corollas.

Even with the 3-speed auto - the 1998 Corolla should have gotten better than the low to mid-twenties in fuel economy. unless it was more city, lower speed driving.

The popping noise could be transmission related - sometimes a trans flush will cause problems, depending on the type of machine used. Since you spun it up in the air and verified the noise - I'd look at the transmission, cv joints, and suspension bits. Don't take the mechanic's word - take a peek youself, most problems can be found by visual inspection or simple tests.

Load start-up noise - like a rattling, knocking, pinging? Could be a belt tensioner - since the newer Corollas seem to have a higher frequency of these going bad. Not really expensive - I'd replace it at the same time you change the serpentince belt. Could also be piston slap or valvetrain noise - may be due to carbon/varnish deposits.

The oil in the PCV valve indicates some oil consumption going on here - could be a baffle is clogged (in valve cover) or damaged, too much oil in crankcase, vacuum leak, or really worn rings (too much blow by). Go easy on the Auto-Rx - some people have had good luck with that, others ended up with a large paperweight when an oil gallery got clogged with junk in the engine. Keep up with oil changes - might want to try oils with higher detergency - like Shell Rotella. High mileage oils are basically synthetic blends with a different additive package - might want to give those or full synthetics a try. New formulations don't have that leaking problem in higher milage engines than the early synthetics.

Try bumping the air pressure in the tire a bit more - they can take 44PSI. But the tire design itself was never intended for max fuel economy - more for noise reduction and ride comfort. Really too high rolling resistance for fuel economy.

Other than that - looks like you on the right track - got all the basic stuff done.

Good Luck.

Guest tenorGJ

Thanks for the speedy replies. Please keep them coming.

I'm not sure about oil consumption--maybe 1/2 quart or so every 5000 miles. What interval would you recommend when using, say, Mobil Drive Clean 5W-30 that gets the new GF-4 rating? 5000 is a nice round number for me.

I believe the crank case was overfilled when I checked the oil. It was well over the full marker. Should I drain off a bit? That was probably my fault when adding the Auto-Rx.

I'll also take a look at the suspension as soon as the weather improves a bit.

Officially, Toyota says a quart per 1000 miles is "normal". It is a little much to me. You really need to keep an eye on oil level at every gas fill up regardless of current consumption rates.

The "popping" noise may be coming from the drive shaft(s) if they haven't been routinely lubricated when brought in for service. Most of the time if a c/v joint is failing the sound can be heard when turning a corner, but the noise can be heard going forward from a standstill also, at times. Check the boots for cracking or loss of grease, or grab one with the vehicle raised and wheels off the ground to check for play. If both shafts look okay, your mechanic is correct and the transmission may be the culprit. Hopefully, when you had the transmission serviced they only did a drain-and-refill instead of a "power flush" which has been known to wreak havoc with a perfectly-working unit afterwards.

Changing the plugs and PCV valve was a good start. The platinum or new iridium-plated plugs will give better performance and economy if you opted for them. I would have also splurged for a fresh set of cables to go with the plugs, just for peace of mind.

I wouldn't worry about the varnish buildup too much. If the oil pressure has always been normal and the oil changed/topped off as needed I don't think this is any cause for concern. However, you can do a Marvel Mystery Oil treatment to alleviate the buildup. Add about 4oz. to the crankcase every time you change the oil and it will act upon reducing those deposits. Use brake cleaner or carb cleaner to remove the varnish from the oil cap and dipstick. You can put the rest of the Marvel Mystery Oil in the fuel tank to lube the fuel pump and injectors too.

Guest tenorGJ

Thanks, Bod,

I was going to ask about plug wires. There's a set available to me--APC, for about $45.00 shipped. Any good? Or should I stick with OEM? I searched for APC and didn't have much luck finding reviews.

I keep meaning to check for plug wire damage when it gets dark.

BTW, I got 4 NGK Rs from Advance Auto for the plug change.

As for the Mystery Oil, I might give it a try, after I've used up the Auto-Rx and Fuel Power products so heavily endorsed on

What about 02 sensors--should I check those? Or would a check engine light come on if they were faulty?

BTW,I checked my oil fill level at work a minute ago and it's not over-filled. I wonder what caused the oil-fouled plugs?

APC is an OK set - there are mostly into improving appearance than anything else - but they do make some quality stuff.

I'd go OEM to be on the safe side - or a brand with a reputation for ignition products if you go aftermarket.

The Marvel Mystery Oil might help - but, same with the Auto-Rx - go easy on it. I've used it for a parts cleaner - really breakups crud. But it would be really bad, if that loosed crud jammed into one of the oil passages. Chances of your motor having that much deposits is unlikely though - should be OK.

As for oil change intervals - depends on the driving conditions. I go with 7.5K to 10K intervals with synthetics - zero problems, but I also drive almost all highway. With the quality of motors oils getting better all the time - 5K should be OK. Remember to change it more often if you use any of these motor oil additives. That dinky filter won't be able to trap much before it goes into bypass operation.

O2 sensors can go bad, without tripping a CEL - if you did all that work and the fuel economy didn't improve - I'd look into replacing the O2 sensors. You can get or rent a scan tool to check operation of the O2 sensors, first - as they are pretty expensive to replace.

Oil fouled plugs - sounds like worn rings,worn valve stem guides/seals, or a plugged PCV valve. If it is carbon deposits or other crud in there - the oil consumption should get worse after all the additives have been worked in.

Good Luck.

I'm not sure what would have caused the oil fouling unless a sticky baffle (as mentioned above) was the culprit, or overfilling. I noticed when I changed the plugs on Wifey's LE that there was a small amount of fouling but nothing to be a cause for concern based on my experiences. The worst that I can recall that has happened with her car is when it ran with about 1/2 a quart (or so) low when I removed the oil filter to replace the starter and forgot to top it off. That may account for the varnish buildup (not too bad, though) that it currently has, although it's approaching 120K miles right now. There was a small amount of oil present around the threads on the plugs, but I couldn't see where any leaks were apparent - I figured that maybe my father-in-law didn't tighten them down enough when he changed them for her two years prior or it was residual spill when he topped it off for her.

Hers still has the original O2 sensor AFAIK, which will give a CHECK ENGINE light when it does fail based on my experience. I wouldn't really worry about that until it happens, as there's no real preventive maintenance for that unless you have $100 burning a hole in your pocket. As far as the plug wires go, I went with the premium set that AutoZone had in stock at the time, which was around $25. If they back up their products with a lifetime warranty that's good enough for me. I don't know too much about APC's products, and I wouldn't spend that for a set of wires in the first place. Get the best ones Advance has to offer for probably half as much and call it done.

While you're at it, you might as well check all the hoses and the serpentine belt, and do a gravity test on the coolant. This would be a good opportunity to make sure she's in good shape for the winter months ahead.

Wifey's LE still runs with the original tensioner and pulley, so I'd suspect a worn belt to be the cause for the noise before I'd condemn the pulley/tensioner. Buy two belts and keep an extra new one for a spare - it's cheap enough and you'll be glad you did in a pinch.

Guest tenorGJ

One last question:

What are the repercussions of not flushing/draining the coolant? I'm not sure it's ever been done. Would that effect mileage? It's not running hot.

I guess it's time to open open the Hayne's one more time...

Thanks for helping out a newbie...

I think the main problems with not changing the coolant are corrosion can build up over time, blocking the effectiveness of the cooling system and the heater core, the lubricative properties of the coolant keeping the water pump lubed, and the pH of the fluid, over time it can drop, increasing corrosion. Oh, and I guess when the fluid is old it doesn't protect against boiling / freezing as good.


I believe you have taken the steps needed to help your engine run efficiently.

I would complete the Auto-RX treatment on your engine and see what the results are, the results will not be immediate.

After the intial flush with the Auto RX, you will need to run an OCI with non-synthetic oil (prefered), depending on the engine, etc., the results will vary,

the Auto-RX may or may not change your mileage.

As for engine oil consumption, there was a TSB placed on these cars, Toyota claimed

the engine would consume more oil when driven at higher freeway speeds.