The "Ask a Mechanic" Thread (merged)

[jwpanic]

QUESTION:

2003 Saab 95 wagon, every time I turn on the AC all my coolant spills into the road and bells and whistles start going off on my dashboard. I refill, drive without AC and everything is fine. Next day, wife gets in car(not knowing about AC problem) same thing happens. How much is this gonna cost me?

Thanks in advance.

[HogNose]

You mean JL might have been LYING to me when they said I needed $100+ in various fluid replacements and flushes every time I went in there?!?

I'm with you man. Haven't been there in 5+ years. If there was anythink like that I actually needed, I would have figured they were just bs-ing me as usual and declined.

Yeah I remember Jiffy Lube trying to tell me I needed my air filter changed and this was a few weeks after I had done it myself.

[SpringfieldSkins]

I have a question. I have a 01' F-150. 4.6L SOHC, Automatic, 4x4. It has 85k on it.

I know Ford makes a junk trans for all of their cars. I have talked to people who have only had problems after their flush, so should I ignore it and just drive it until I have a problem, like I am certain I will eventually.

Also, I will usually change my timing chain and redo to heads at 100k, but seeing as I have no faith in my motor, should I ignore that until I have problems as well?

I slipped the chain towing my derby car to the bone yard once, but after putting the correct, thin as piss oil in it, it was fine. I know the new Ford motors have a pin hole to oil the chain and I having always driven older iron, had 10-40 in it. I'm on 5-20 now and haven't had a problem again. That was 20 k ago.

Seeing as how you have a bit of an automotive background, I'll be a little more techy with you...

I don't like Ford, never have and probably never will. My girlfriend drives a Focus and I had to replace the motor in it at 90K, the top of piston #2 just decided to break off of the connecting rod... pretty cool.

That said, Ford's transmissions aren't nearly as much of junk as the transmission in Chryslers or some newer Hondas (althugh, it seems that the Honda ATF Z-1 plays a large part in that). I take it you have never flushed your transmission before. I've certainly seen my fair share of ATF flushes that seemingly caused the transmission to go bad. Those ATF flushes only exceeded the inevidable though, those transmissions were toast long before we flushed them. A transmission flush on a good trans, that's not in the process of failing is always a good thing, you want the inside of that bad boy to be pristene clean.

So look at your transmission fluid... Does it have metal flakes in it? Is it jet black? If not, and your transmission isn't slipping, I see no harm in a flush. If you flush it and 6 months later your transmission dies, it would've happened anyway, just a little faster because the flush cleaned all of the dirt and grime that was holding your transmission together out.

As far as timing chains, I don't see any point in changing them unless they break or there is so much slack that the valve timing is way out of whack. Just my personal opinion.

And yes, most if not all, new Fords take 5W20. The oil is thin as hell and may scare you, but I've heard of 2.0L Ford engines lock up because somebody decided to use 5W30 instead (the camshaft locked up). Look at it this way, the 5W20 is a fuel saving oil... it'll help save gas on that giant, gas guzzling V-8 that you have.

[SpringfieldSkins]

While idleing my car starts make a screaching sound that gets louder and then stops.
Kids think the car is going to explode.
Never happens when moving. Someone said belt:

94 volvo 740

Sounds like a belt to me. Check the belt condition and tension on the belts. Could certainly be something else because there are 1,000 (not literally) things on a car that could make a "screaching sound that gets louder and then stops". The belt would be the first thing I would check, depending on how I interpreted the noise if I heard it in person.

[SpringfieldSkins]

Well, i dont own a hot rod, truck, or piece of junk. Maybe just let the OP handle the questions.

Anybody else who wants to field some questions and think you know what you are talking about can go ahead. If I see something that I percieve to be wrong, I'll try and correct it.

[SpringfieldSkins]

QUESTION:

I have a 2007 Subaru Forrester XT Sport. It has a turbocharger and "requires" premium gas (93). What would happen if i put regular in (87)? My manual says very bad things. However, i read online in a forum that since the late 1980s, there has been a law requiring automakers to make all their cars run on regular gas. Allegedly, if i put 87 in, not only will i be saving money on gas, but i will get better gas mileage due to the turbocharger being shut off (when the sensors detect 87 instead of 93). is this claim true or bogus. it would be GREAT to save some money on gas, even if it comes at the expense of performance.

Short answer: Use the premium gas.


Long answer: First I will explain the basic theory of the turbocharger... After the exhasut manifold there is a turbocharger in the exhaust coming from the engine. Inside the turbo, there are vanes (think pinwheel that you used to blow on as a kid that would sping when you blew at it), that spin with the gas that is being exhausted from the engine. These vanes are connected to the intake (which sucks air into the engine) and help suck more air in as the engine RPM increases and the vanes spin faster and faster. The more air you can fit into the engine (combustion chamber) the better, because more air means more gas which means bigger (read more powerfull) combustion or explosion. This increases horespower at higher RPM (or however the turbo is designed to be most efficient) as opposed to a naturally asparated engine (non-turbo and non-supercharger).

Why regular gas isn't good on your turbocharged engine... Gas is rated on it's resistance to spark knock or predetonation. The combustion process is supposed to start when the spark plug fires, I think that's fairly common knowledge to assume. If the temperature is too hot in the combustion chamber the air/fuel mixture will ignite all by itself without a spark from the spark plug. 93 Premium fuel is more resistant to this when compaired to 87 or 89 octane. When all of this air is forced into the engine from your turbo (or supercharger, or just high compression ratio) it will heat up, more air compressed means more heat. 87 Octane has a much higher chance of preigniting than 93.

Now... Why preignition isn't good for your turbocharger or engine in general. As far as the engine is concerned, preignition will cause the air/fuel mixutre to ignite before the piston gets to the top of it's travel and much too soon. This means the piston is being forced back down even before it's at the top and it will still need to travel to the top even under the pressure of it being forced back down. This means bad news for things like the bearings that carry all of the load on the engine while the crankshaft is moving, basically much, much premature wear. As far as your turbo is concerned... this preignition will also hurt that. If the air/fuel mixture preignites with the valves still open, it will want to push the combustion out any exit from the combustion chamber it can find, possibly to those turbo vanes. Soon enough those turbo vanes will be nonexistent and you won't have that fun boost of power when your car is revving up. A turbo rebuild is mighty expensive too I might add.

Lastly (I think), the turbo does have protection from building up too much pressure. A Blow off valve, wastegate or whatever you want to call it. It releases excessive pressure in the system to prevent damage to either the turbo or the engine. This may help if you decide to use 87 octane in your turbocharged car, it may not, I can't honestly say.

If it were my car, I'd use 93 octane, just like the engineers who designed the car wanted.

[SpringfieldSkins]

my take on these issues is strictly financial... 93 is about 30 cents more expensive than 87. in a 20 gallon tank, that's an extra $6 for the high octane. if you run through 2 tanks per week (a lot in my world... i only fill up twice a month), it's only an extra $625 for that gas. a lot of money, but not that much compared to just about any mech work done on your engine.

Exactly... It would cost much, much more to rebuild or replace that turbo. It ain't cheap guys.

[SpringfieldSkins]

I just paid 650.00 to have a new alternator and battery installed. How big of a sucker am I?

98 ford exploder..

That sounds fairly close for your area... Assuming you got good quality parts of course.


Another thing to remember as far as the car repair costs... The vary by area a WHOLE (that's right, I used caps and underline ) lot. What costs $200 somewhere, may end up like something more in the area of $500 somewhere else in the country.

In my area, prices are sky high, sucks for the consumer but good for me.

[twa]

Ignition in my car will not turn back all the way. At first I could play with it and get it to turn completely off and get the key out like normal. Now it will not return to the off position. I had to leave it like that when I got home last night and shocker, my battery is cooked now.

I'll charge it back up and try again. Any chance there's something that an impatient, not very mechanically minded person might be able to do without paying a ton?

Get a can of WD-40 and use the straw to flush out the lock cylinder(then jiggle ),perhaps you will get lucky.
It is either dirty or worn key or cylinder(or all of the above),if the key looks worn try another.

Type of car would help,some are inexpensive some not at all.

[SpringfieldSkins]

i have a 2005 Cadillac CTS-V. It says to use 93 octane in the book. Its not turbo charged or anything but it has a 5.7L Corvette LT1 engine in it. Could I use a lower octane without messing it up. Also I bought it used with 45k on it. Are there any special services I should get done on it. I just bought it a month ago an Im not sure what has been done recently. Thanks in advance.

Nice car choice, first of all...

Guys, I'll have to say this (and not directed at stoney)... If the manual says "Premium Unleaded Only", please use it. I know gas is expensive, it's a damn shame, but the 30 extra cents per gallon are well worth it. It would probably cost you $8000 to have that motor replaced stoney, is that risk worth the extra $1000 you would spend on gas a year?


That engine, if I'm not mistaken, has a fairly high compresson ratio. Meaning that all of the air that is sucked into the engine is compressed into a very tiny space. All of that compression (a lot of air in a small space) makes the temperature of that air/fuel charge very high. High enough compression and you will cause preignition at lower octanes. Read the post a few above for more about octane ratings.

Long story short, you should use 93 on that car.


As far as your mileage services, it's probably nothing more than an air filter or cabin filter. Check your owners manual. Cadillacs are surprisingly light on maintenance if I remember correctly. Of course have the brakes, tires, belt, hoses, fluids and stuff checked too.

[speardog1]

Personally, I don't bother selling them or the stupid power steering flush because I think they're just ways to get money out of your pocket into mine. That doesn't fly with me.

I agree with this. As soon as a service person tries to sell me a power steering flush I typically will never go back to them. I always thought that was BS. Apparently, my suspicians were correct.

Question. My girl has a 97 corolla with 90K, which should get in the 30's in terms of mpg. I bet it gets in the low 20's at the moment, horrible. I changed the plugs and wires, no effect. What should I do next? Fuel system cleaning?

[SpringfieldSkins]

started a thread on this not too long ago, haven't done anything to address the problem yet. Wondering if I'll get the same answer from you...



I've got a 99 accord ex, about 160k miles. Auto transmission

Lately, sometimes if I have to hit the gas to reverse up an incline, I'm going a couple feet and then it's like I'm between reverse and neutral. Engine revs hard but I don't go very far (but don't roll forward either). If I put it into drive and then back into reverse, it will either work fine, or do the same thing again (back a couple feet, then nothing). No problems idling in reverse out of a space or in drive. It has happened once or twice on very slight inclines, but for the most part it's only happening on bigger inclines with no troubles on flat surface. Transmission fluid level is fine.

Thoughts?

I don't know what answers you got on the other thread, but to me it sounds like your going to need a transmission soon. Sounds to me like what you are describing is the transmission slipping, which on an automatic is not good, especially if the fluid level is fine.

Your saving grace is that this is only happening in reverese, which you don't need to use hardly at all. I would guess this problem will get worse and worse over time, hopefully this doesn't happen to your forward moving gears (most of the Honda transmission failures happen in drive gears).

That's my thought, although you can't be too sure unless you actually have it checked out. I'd bet the might try flushing the transmission (or drain and fill, if your car has no cooler lines) and if that is unsuccessful you'll have a bill for a new transmisison on your hands. A flush certainly could cause your otherwise normally working transmission to go to **** in this situation though, just to give you a heads up. Either way, sounds like a transmission replacement is in your future my friend.

[SpringfieldSkins]

Ignition in my car will not turn back all the way. At first I could play with it and get it to turn completely off and get the key out like normal. Now it will not return to the off position. I had to leave it like that when I got home last night and shocker, my battery is cooked now.

I'll charge it back up and try again. Any chance there's something that an impatient, not very mechanically minded person might be able to do without paying a ton?

As twa said, you could certainly try the WD-40. Spray it into the ignition lock (where you put the key) and turn a few times, see if that helps. I doubt it will and you will probably need to get the ignition lock or switch replaced, but it's worth a shot.

[SpringfieldSkins]

SS-


I change my oil every 5,000-6,000 miles because I have heard it is actually better for the engine and my owners manual actually says 5,000. The 3,000 miles from what I have heard is too soon and is just an industry standard set to get people to bring their cars into the shop sooner. What is your take on it?




BTW, can you tell me why Jiffy Lube is still in business? The last time I was in a Jiffy Lube was 3 years ago and I never went back after Honda said they hadn't changed my oil filter. Do you and others in your line of work look down on them as many of us do? I have read a lot of bad press about that company and I wonder how they can stay in business. God damn bunch of crooks. They seem to employee people that only have burger flipping skills.

I personally change my oil every 3,000 miles, or at least I did on my old car, running conventional oil. When I switch my new car over to Mobil 1, I'll be changine my oil ever 5,000 miles.

I think, back on page 1 or 2, I had a nice little rundown of the difference between conventional oil and synthetic oil. Long story short, Synthetic has no sulfur which means the oil won't brake down nearly as quick when compaired to conventianl oil. When oil breaks down, it's because sulfuric acid builds up in the oil which then eats away at the additives in the oil (friction modifiers, seal conditioners, etc.). A broken down oil doesn't lubricate very well and will cause leaks and such. I can't say confidently that you're not safe at 5,000 miles, but I can't say confidently that you are either. I know for a fact, at 3,000 miles, on conventional oil, you are still safe.

So I perfer the 3,000 mile oil change interval. Hell, it's less costly than a tank of gas. If they want to sell you something when you are there, just say no, plain and simple, or a good line like "OK, I'm going to have my mechanic check it out.", that will make them shut right up.



As far as the old Jiffy Lube... they're still in business because they are making a boatload of money. They are making more money than the dealerships and the private shops combined. They do this with things like upselling and time efficiency. People can be talked into pretty much anything and time is usually of the upmost importance. Come to my shop, well have your oil changed in 30 minutes to an hour in most cases. Go to the old Jiffy Lube and you're in and out with in 15 minutes in most cases. Were more honest and personable at my shop, but who cares when time is at stake?

Yes, I do look down on Jiffy Lube. You can teach a monkey to do the things they do to a car if you had 30 minutes. They are mostly unskilled and not very knowledgable. Their saving grace is that they have the assembly line oil change down to a tee.

[Bliz]

I don't know what answers you got on the other thread, but to me it sounds like your going to need a transmission soon. Sounds to me like what you are describing is the transmission slipping, which on an automatic is not good, especially if the fluid level is fine.

Your saving grace is that this is only happening in reverese, which you don't need to use hardly at all. I would guess this problem will get worse and worse over time, hopefully this doesn't happen to your forward moving gears (most of the Honda transmission failures happen in drive gears).

That's my thought, although you can't be too sure unless you actually have it checked out. I'd bet the might try flushing the transmission (or drain and fill, if your car has no cooler lines) and if that is unsuccessful you'll have a bill for a new transmisison on your hands. A flush certainly could cause your otherwise normally working transmission to go to **** in this situation though, just to give you a heads up. Either way, sounds like a transmission replacement is in your future my friend.

...

Probably cost near as much as the car is worth, but having JUST bought my wife a new one, and a baby due in 6 weeks I'd glady spend the $2-$3k if it will keep me going at least another two years.

Thanks man. Great thread that clearly a lot of people are getting good use out of.