View Full Version : AAaaarrrgggghh I wish I was a mechanic

2nd November 2000, 12:19
Great I've got two garages (One being the warrenty holder) arguing whether my car is buggered or not. Each one calls the other an idiot and they don't know what other are talking about.
According to one the inlet manifold is leaking and this is before the Lambda sensor which then makes the correction. The other says this is complete bullshit and the sensor won't be able to correct this.
I've now taking the car to Renault dealer whos going to check things out and the dealer whos got the warrenty I going to pay for any work.

2nd November 2000, 13:21
What kind of car are we talking about, btw?
Tried the forum on your brands car-site already http://forums.murc.ws/ubb/wink.gif

Brian R.
2nd November 2000, 14:45
Bet it's a Renault. http://forums.murc.ws/ubb/smile.gif

2nd November 2000, 17:53
It's a Renault. Heh.

But seriously, if your Intake manifold is knockered, there's NOTHING any sensor can do to "compensate" or "fix" it. You need... wait for it... a NEW INTAKE MANIFOLD.

And... err... is this an extended warranty? If it's a new car warranty it doesn't matter where you take it - just take it to the nearest Renault dealer.

- Gurm

Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

2nd November 2000, 18:17
I'm so glad they stopped importing those things to the states over a decade ago. Almost all of em have died now, so you don't even see too many of em on the roads these days here. I spent many years working parts in a Renault dealership. The French make many things well (food, booze, women, art, etc.). Cars is NOT on this list http://forums.murc.ws/ubb/wink.gif

Brian R.
3rd November 2000, 00:28
Gurm - Think intake manifold gasket... http://forums.murc.ws/ubb/smile.gif

3rd November 2000, 01:28
How about those fast idle problems too.

Remember when Motor Trend named it Car of the Year?

3rd November 2000, 06:02
It's a Renault Clio. Intersting about your comments and we've never had a prob til now. It's my first renu but the rest of the family used them without probs.
It is the inlet manifold gasket thats suspect by the way.
Warrenties since it's a used car most things aren't covered. Normally it's the bolt on the back thats covered. I've done well to without having to be threatning to get he exhaust replaced and speedo cable. Also when claiming on the warrenty your dealer is the first port of a call over here anyway.
But when you got Two sets of mechanics saying each other are plonkers theres not a lot you can do bar going to a third party and then sue the bastereds the warrenty is with.

3rd November 2000, 07:49
Ahh... ok, well the intake manifold gasket will need replacing then. There's no "sensor" that "fixes it".

But, it's a good bit cheaper than a new manifold, although potentially labour intensive (dunno how hard it is to get a manifold off and back on again in a Renault).

- Gurm

Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

3rd November 2000, 08:30
I think the lamba sensor may be able to compensate for (not fix, compensate for) a blowing inlet manifold gasket to an extent, provided its a very small leak.

Fundamentally, the leak just messes up the fuel/air mixture and I think that the sensor can instruct the electronic fuel injection to adjust the mixture according to the contents of the exhaust gasses (I'm not that great with modern engines, A-series from my Mini is more what I'm used to http://forums.murc.ws/ubb/smile.gif)

You will probably lose a bit of performance and economy too. The situation is only gonna get worse http://forums.murc.ws/ubb/frown.gif

[This message has been edited by Raptor^ (edited 03 November 2000).]

3rd November 2000, 09:00
Yes, sorry. A bit of a retraction of my earlier stance.

It can be compensated for, but only in very small amounts. Normal leakage, or improper fit, or a very small crack. Basically the lambda sensor is designed to not leave you stranded when you get a shitty fuel/air ratio due to a gasket going bad.

But once the crack gets big enough, nothing can fix it except a new gasket. The gasket itself is cheap (just rubber) but in some cars it takes a bit of doing to get installed.

- Gurm

Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

3rd November 2000, 12:05
Well one nice thing about the warrenty I've got roadside recovery. So if the car is ****ed I just ring up recovery. According to the garage thats says that theres nothing wrong the Lambda sensor can't compensate. Driving it I feel theres something wrong the fuel comp is shit round town and if you want the darn thing to move at 60mph you've got the foot to the floor and keep it there which for a small car with supposed 80bp is shit.
I'll just wait for the 3rd garage and I'll have a look myself tomorrow weather permitting if I see something I'll mark the darn thing up with chalk and say suck that you dummies.

11th November 2000, 18:20
The Pit,

Lambda sensor, I take it that is what europe calls an "Oxygen Sensor". Oxygen sensors do only one thing: they measure the difference in oxygen between the atmosphere and the oxygen in the exhaust stream by puting the sensor in the exhaust stream. The sensor changes the voltage it produces depending on how much oxygen is in the exhaust stream. The computer in your car reads this voltage and determines, along with many other factors, what the injector pulsewidth(s) should be. The computer is programmed with certain parameters in mind, to determine what is running rich under which condition, and what is running lean under certain conditions. Having a vacuum leak that is detectable throws the whole strategy out of whack. It can even cause more severe problems if the vacuum leak is isolated to one cylinder, rather than distributed amongst all (four?) of them. The sensor cannot know which cylinder is running lean, therefore cannot compensate directly for that cylinder. If the leak is divided amongst the cylinders evenly, then you are puting an unnecessary load on your engine. While driving down the road, the computer sees the vacuum is low for what is expected with your current throttle position, and would richen and advance the timing at the same time to give more power, this causes more heat in your cylinders and heads, and also causes a decrease in your gas mileage. If the leak is severe enough, it can cause damage to your exhaust valves, and damage your catalytic converter (if yours has one). There are many other possiblities for damage. In short, if there is a leak, get it fixed, and have it fixed properly. A leaking intake should be removed, cleaned and checked with a straight edge for warping, and the cylinder head's intake facing should also be checked at this time. The intake should also be thoroughly inspected for cracking, or loose vacuum fittings. But don't let this go, get it fixed.


12th November 2000, 14:31
Well answered Rags. I was going to say pretty much the same thing, specially since its under warrenty.

Also remember if there is an air leak, then that air isnt going through your air-filter.

Even little bits of dust into the bore is not good news. (trust me, the K&N fell off my Cooper S once, and F***ed a stage 3 engine that had only done 1000 Miles).


13th November 2000, 00:51
Thanks for the info. Well another garage looked at it A Renu dealer checked it all out and found nothing wrong. I checked it myself before they did and couldn't see anything.
Strangly the car seems to be running better even though they said they hadn't done anything so go and figure.

13th November 2000, 19:35

Better only due to wet weather.

Get the Damn leak fixed...or at the very least document your problem better than on this forum for warranty purposes.

I know nothing about Renaults, but leaking gaskets on Aluminum blocks are notorious. I work in the recycling business, and we grind up far more aluminum block cars as scrap and at a much earlier age just for this issue.

Did your little car ever run hot?? Even one event of this sort can cause warpage that NEEDS REPAIR!!

14th November 2000, 13:35
As for the wet weather it's dry for the last few days and it's still running fine. Three garages checked it one found a fault (first one) two didn't I've checked the same way first one did and didn't find anything either.

14th November 2000, 19:46
The good thing about mechanical systems (cars) is that there is ALWAYS an ultimate answer. If it's running fine now, in the absence of other variables, I'd refer to the posts above about the lambda sensor and assume that your problem is SILICON based.

In an ideal world (Heh!) there would be no digital control of a purely mechanical system unless you control EVERYTHING about the environment in which the digital system operates.

Impossible in the real world. Cars are mechanical systems.

If it is an intermittent problem, look to systems that operate intermittently-> silicon. (Some computer or digitally controlled parameter)

15th November 2000, 02:08
The PIT, I hope your not serious...you don't really want to be a mechanic now, do you? I have been doing it for 29 years and I would like you to reconsider....

Of course we are called technicians now, whether some of us deserve the title or not...

If you suspect an intake leak, attach a length of vacumn hose to a propane torch that you have removed the torch nozzle. Crack open the valve a bit and direct the hose around the intake where it attaches to the head. If there is a leak, the propane will be sucked in and noticably smooth the idle.
Vacumn lines and hoses, injector o rings (if applicable) are all suspect. Vacumn power brake chambers (if so equipped) can leak intermittently too.

If it comes and goes, check manifold bolts for torque. Other than other reasons mentioned, loose bolts are one cause of intake gaskets sucking in.
The list goes on and on.

Or you can spray carb cleaner all over the engine and if it ignites, back off and... Never mind, don't check for a vacumn leak this way.

[This message has been edited by SCompRacer (edited 15 November 2000).]

15th November 2000, 20:09
To any and all techs out there!

How many times have you found the "problem" to be a mechanical one, vs. some ethereal digital or transistor-based problem.

Case in point: I'd hazard a guess that 1/3 of all "bad board" problems relate directly back to a cold solder joint, or a heat related problem that is easily corected by mechanical means.

My entire home stereo system is built on people-with-too-much-money-who-throw-away-their-stuff-that-doesn't-work-right-and-they-don't-know-why.

It has been a good deal for me and my trusy soldering iron.

The Pit...you have my sympathies...I wish you well.

Mechanics are commonly the scum of the earth, and if you find one you can trust, you MUST attach yourself to him forever and slavishly follow his advice for life--no matter what the cost. http://forums.murc.ws/ubb/smile.gif http://forums.murc.ws/ubb/smile.gif

15th November 2000, 20:45
Okay now here we go again with judging people by their profession. I totally disagree with the notion that you can judge a person by what they do for a legal living.

Let's get something straight. It's not easy to repair automobiles anymore. This isn't 1969 anymore, and there is no such thing as a simple auto, and there is definitely a much wider variety of cars to work on. With each different make of car, comes a different theory of Electrical/Electronic/Fuel/Air Induction/Suspension-Steering/Emission Control, etc. It is expected of technicians of today to know each one of these systems inside-out, diagnose the first time, repair the vehicle timely, and do the work right the first time. Most Techs work off of some sort of "Flat-Rate", where they get paid depending on how long a job "should" take. This means that a guy/gal working in a shop must be able to diagnose an obscure fuel injection problem properly in about an hour or under, make a determination on the best route to repair, prepare a fair estimate, perform repairs, check repairs, and test drive thoroughly to confirm the diagnosis was correct all within the time alotted. Then he may have to work on a rear differential afterwards, and is expected to do all these repairs within flatrate time, or else he starves. Then you have the public who overall know absolutely nothing about how cars work, and expect everything to be simple, cheap, fast, accurately. If one of these things fail to meet his/her expectation, then the tech/shop is unqualified/crooked/overpriced/slow/incompetent.

I think the general public needs to wise up. Are there some shady techs out there? Sure, but they don't last long at any one place, believe me. Stay away from the places that would be more prone to employee turnover: Franchise Repair Shops, etc. And before deciding on a place to repair your vehicle, do some research including talking with the techs themselves and find out how long they have been working there. If you ever doubt a diagnosis, get a second opinion, it will cost you but it's peace of mind.


15th November 2000, 21:22

Of course you are correct.

If Car repairmen were trained in proportion to the knowlege required, there would be a whole different situation.

Unfortunately, this isn't so. Which is why I said that if you for any reason actually FIND such a competent mechanic, he is to be cherished and trusted completely for life. http://forums.murc.ws/ubb/smile.gif

This relates directly to why I am a Matrox fan. This is the first company where I found honest, realistic, and responsive support. I could care less which card has the last FPS...I know that with this organization, I will get support, or answers. If I trust a mechanic who says "here is why this engine is a piece of **** and should be replaced"...at least I'm getting an answer.

That means more than anything else to me.

15th November 2000, 22:27
As far as scum goes, I have had some customers that fell into that category.

Had an underhood type service shop for a couple of years till I opted to go back into fleet work as the patience required to deal with about 15-20% of people was quickly fading.

No matter what questions you asked "there were no problems with car, just decided it needed a tune up." Big mistake to do anything until you stuck a four gas probe up the tailpipe and scanned the computer for codes. Tune it first and "ever since you tuned it, it fails emissions testing, or it doesn't start in morning, or..."

Or they show for an appointment and don't shut the car off and even offer to drive it in for you. One of my guys drove a car in that was running, shut it off and the car would not restart. "What did you do to my car?"

"Why do you need diagnosis time, those machines tell you everything thats wrong with the car!"

"You put the wrong spark plug into my car!" No sir, that plug has been discontinued by GM and this is the replacement number...here it is in the AC Catalog." "I don't care, I want this number in there!"

Ask them if it runs rough in the rain. "Oh no." Spray the plug wires with a mist of water from a spray bottle and it runs rough or dies, indicating bad plug wires. "What did you do to my car?"

"Ever since you worked on my car the tape player doesn't work."

So there are dishonest people on both sides. Your training in proportion to knowledge needs to include a degree in Psychology as well as law these days.

15th November 2000, 22:51
Some of my favorites:
C=customer, R=repair shop
C-"you changed my oil two weeks ago, now my check engine light is on, you are going to fix whatever you f'ed up"

C-"my car's wipers turn on when I push in the cig. lighter, and the alarm goes off by itself at times"
R-"The diagnosis starts with a base of 1Hr, which includes visual, basic, and scan testing. If nothing is pinpointed from these tests, additional time will be needed and charged accordingly"
C-"What???? You expect me to pay for you to just tell me what's wrong with my car? Just hook it up to your computer and tell me what's wrong, I am not paying just to have you look at it"
R-"Dr. ****(actual name not included here), you charge people to make an appointment at your office, correct? Then you charge them for lab tests, correct?"
C-"Uhh...yeah...but that's different, I have my own practice, pHD, yada yada yada"
R-"Our price is 55 dollars an hour, will you be paying with cash or credit card?"

C-"My car is making a noise while driving"
R-"What kind of noise, where is it coming from, and when does it do it"
C-"it's a loud noise coming from my car while driving"

C-"My Service Engine Soon light is on."
R-"We checked it out, and found that the light was caused by a gross leak in your evap. emissions system, we found that you had your gas cap loose. We charge an hour at 55 dollars an hour for diagnosis, and didn't charge you for tightening your gas cap, and fixing a pinched return line, your bill is 55 dollars"
C-"55 dollars???? For tightening a gas cap??? what kind of operation are you running here? You guys are out of your minds!"

C-"My car dies intermittantly, how much do you charge to fix it?"
R-"For us to start diagnosis, it is 1 hr at 55/ hr, then we charge 55/hr for repairs and additional diagnosis plus parts"
C-"I am NOT paying for any diagnosis, my brother told me it is my ignition module, and is no big deal to repair"
R-"Do you want us to put an ignition module on? It will cost you 1.5 hrs and 125 for the part, and will not guarantee it fixes your dying problem."
C-"I want you to fix it properly, that's what I want!!"
R--"For us to start diagnosis, it is 1 hr at 55/ hr, then we charge 55/hr for repairs and additional diagnosis plus parts"

Oh, there are many more. These are actual happenings I have witnessed in the last month.


17th November 2000, 08:02

I'll repeat again, an honest, competent, knowledgable, professional auto mechanic is someone to be cherished and trusted for life. And the biggest reason there are so many unscrupulous ones is because it is so EASY to perform unneeded repairs or shotgun the problem by replacing half an engine.

I'd gladly pay you the diagnostic charge...in fact, it should be a savings if this allows you to pinpoint the problem and get the work done. I've got a feeling that if you're any good at what you do, you've got all the work you can handle anyway.

My main rant has to do with the general conduct and policy of franchise shops...and you know what I mean, cause I bet a large number of your customers come from first pulling it into the local midas or wal-mart.

http://forums.murc.ws/ubb/smile.gif http://forums.murc.ws/ubb/smile.gif