Ben, why not buy them at Stuttgart while you rae there? buy the liners etc too and come fit them when you return. you will still have time for the show! just start on the rest of the car and leave the engine for last.
that is what i would do. but then, that's me.
mike
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I usually just pull the plug and test the contacts for continuity to ground. It won't identify the weak ones but it will pick up the dead ones.
This is all very good .
Another quick & dirty way is to buy a $20 Infra Red Thermometer from Harbor Freight and shine it at the base of each glow plug where it screws into the cylinder head , as the relay is on , engine cold ~ this way NO BURNS (it cannot be overstressed how badly a Glow Plug will burn you !!) , if the thermometer shows a lot of heat , shine it on the next glow plug , when you find some that are not blistering hot , those are the bad ones .
For the labor involved I prefer to change them all at once .
Monark brand gets the nod over the current Bosch crap ones .
Always , _ALWAYS_ use a closed end wrench to loosen them , I think a ratcheting box end wrench is prolly the easiet way to do them .
-Nate
Bogy wrote :
>
> Let's see:
>
> Yes you should have pulled the plug before doing a resistance test. What you were testing is all the plugs together and if one is good then that is the one that you are testing. If, say, two of them have opened up, then the remaining three will still show a connection. You have to resistance test them individually. And even then a low resistance does not mean they will work. The only real way to test them is by measuring the current they use, and that has to be measured for each individual plug.
>
> Also, the fact that they are getting 12 volts does not mean that any current is flowing. It only means that the supply wire is intact. Remember that a disconnected battery shows 12 volts across it's open terminals. But there is still no current flowing. 12 volts at an open glow plug doesn't tell you anything useful.
>
> By the way, most electrical problems are not short circuits, or shorts. Most electrical problems are open circuits. That's when the wire breaks, or the transistor stops conducting, or the light bulb filament breaks, and no current flows. This is how glow plugs commonly fail. They burn out and open up. They get too hot and the resistance element inside them melts or evaporates or fizzles away and opens up. In the rare case that they melt and "short", the fuse would blow from too much current flowing.
>
> When all the plugs are working, you can turn the key on with the door open and watch the dome light dim down a bit. This is because they will pull enough current to materially affect the battery voltage, and the light will dim down a bit. Then, when the relay turns off (opens the circuit) the dome light will get a little brighter. Now one glow plug may or may not have this effect. But if it does then that is an indication that it is pulling current and may be good. Again, the only real way to tell for sure is with a current measuring meter.
>
> So here is a simple and uncalibrated way to measure current: get a small (1 inch or so) and relatively weak bar magnet and "attach a thread to each end". I put that in quotes because you can tape the middle of a long (24" or so) piece of thread to the magnet. Hang the magnet by the two threads, forming the shape of the letter "V". Hold it over the wire under test, at 90 degrees to the wire, and one inch above the wire. Then have a friend turn the key. The magnet will want to align with the wire if current is flowing. The more current flowing, the stronger it will 'snap' into alignment with the wire. This is how large DC ammeters are made. Except that they attach the magnet to a spring and an indicator needle. But you should be able to tell the difference between good glow plugs and bad ones by the difference in response.
>
> Otherwise, you could pull them all out and energize them to see if they get hot. It is actually fun to watch. Or you could turn the key on when the engine is cold and touch a crayon or candle to the exposed end to see if they have gotten hot. (CAUTION: BURN WARNING! TRY AT YOUR OWN RISK!) The good ones will get hot and melt the candle.
>
> Okay, here is one more possibility. Unplug the bigger glow plug wire plug at the relay. Then you could touch a hot wire from the battery to each individual glow plug, one at a time, and observe the size of the spark produced. Weak sparks mean low current and bad plugs.
>
> But unscrewing each plug is the most sure way for the novice to test his glow plugs.
>
> That's it. I'm out of tricks.
>
> Bogy.
>
>
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I never pull the plugs to test. Just pull the plug connector at the
relay, and check ohms from this plug to ground. Each glow plug is
numbered on the plastic plug, though small type. As others said, at
least 2 will stand out as bad; good being "0" or close, and bad
something else. The test is simple, replacing #5 is a pain.
Rob
'85 300D
Garden Grove, CA
==
On 2/12/13 10:28 AM, diesel_mercedes@yahoogroups.com wrote:
> Re: glow plug problem Posted by: "Bogy Wan Kenobi"
> polespearbogy@yahoo.com polespearbogy Date: Tue Feb 12, 2013 10:07 am
> ((PST)) Let's see: Yes you should have pulled the plug before doing a
> resistance test. What you were testing is all the plugs together and
> if one is good then that is the one that you are testing. If, say, two
> of them have opened up, then the remaining three will still show a
> connection. You have to resistance test them individually. And even
> then a low resistance does not mean they will work. The only real way
> to test them is by measuring the current they use, and that has to be
> measured for each individual plug. Also, the fact that they are
> getting 12 volts does not mean that any current is flowing. It only
> means that the supply wire is intact. Remember that a disconnected
> battery shows 12 volts across it's open terminals. But there is still
> no current flowing. 12 volts at an open glow plug doesn't tell you
> anything useful. By the way, most electrical problems are not short
> circuits, or shorts. Most electrical problems are open circuits.
> That's when the wire breaks, or the transistor stops conducting, or
> the light bulb filament breaks, and no current flows. This is how glow
> plugs commonly fail. They burn out and open up. They get too hot and
> the resistance element inside them melts or evaporates or fizzles away
> and opens up. In the rare case that they melt and "short", the fuse
> would blow from too much current flowing. When all the plugs are
> working, you can turn the key on with the door open and watch the dome
> light dim down a bit. This is because they will pull enough current to
> materially affect the battery voltage, and the light will dim down a
> bit. Then, when the relay turns off (opens the circuit) the dome light
> will get a little brighter. Now one glow plug may or may not have this
> effect. But if it does then that is an indication that it is pulling
> current and may be good. Again, the only real way to tell for sure is
> with a current measuring meter. So here is a simple and uncalibrated
> way to measure current: get a small (1 inch or so) and relatively weak
> bar magnet and "attach a thread to each end". I put that in quotes
> because you can tape the middle of a long (24" or so) piece of thread
> to the magnet. Hang the magnet by the two threads, forming the shape
> of the letter "V". Hold it over the wire under test, at 90 degrees to
> the wire, and one inch above the wire. Then have a friend turn the
> key. The magnet will want to align with the wire if current is
> flowing. The more current flowing, the stronger it will 'snap' into
> alignment with the wire. This is how large DC ammeters are made.
> Except that they attach the magnet to a spring and an indicator
> needle. But you should be able to tell the difference between good
> glow plugs and bad ones by the difference in response. Otherwise, you
> could pull them all out and energize them to see if they get hot. It
> is actually fun to watch. Or you could turn the key on when the engine
> is cold and touch a crayon or candle to the exposed end to see if they
> have gotten hot. (CAUTION: BURN WARNING! TRY AT YOUR OWN RISK!) The
> good ones will get hot and melt the candle. Okay, here is one more
> possibility. Unplug the bigger glow plug wire plug at the relay. Then
> you could touch a hot wire from the battery to each individual glow
> plug, one at a time, and observe the size of the spark produced. Weak
> sparks mean low current and bad plugs. But unscrewing each plug is the
> most sure way for the novice to test his glow plugs. That's it. I'm
> out of tricks. Bogy. --- On Tue, 2/12/13, bmwsid
> sidcranston@yahoo.com> wrote:
>> >OK, Had a beautiful day
>> >yesterday. I tested each glow plug right after turning
>> >the switch on. Each one was getting 12 V.
>> >I then tested with an ohm meter between the engine, and the
>> >electrical connector with the wire on it, and most of them
>> >were '0', one or two were .1
>> >Was it necessary to unplug the other end of those wires
>> >first? I didn't, because it was on there pretty good,
>> >and I was leery about breaking anything. Does it just
>> >pull straight away?
>> >It is very clean in there, so there is not a corrosion
>> >problem, and the fuse was nice and shiny, and tight. Car
>> >still wouldn't start.
>> > Sid, near Niagara Falls
>> >
>> >--- Indiesel_mercedes@yahoogroups.com,
>> >Bogy Wan Kenobi wrote:
>>> > >
>>> > >If the dash light didn't come on you should suspect
>> >that at least two plugs are dead. And maybe three. There is
>> >a relay and control box under the hood on the left inner
>> >fender well near the left headlight - about 12 inches back
>> >from the headlight. It should b3 under a plastic form fitted
>> >cover. It has two plugs - one with smaller-ish wires and one
>> >with 5 larger-ish ones. The plug with the 5 larger wires is
>> >the feed for the glow plugs themselves. You will need to
>> >unplug that plug to test the glow plugs individually. Their
>> >resistance is near zero ohms to begin with so an ohm meter
>> >will only help detect an open plug. A shorted plug will
>> >likely blow the big fuse at the "rear" end of the relay. The
>> >best way to test them is with a DC ammeter under power. Each
>> >working plug should pull between 8 and 12 amps. A wire from
>> >the battery through an ammeter and to each plug, one at a
>> >time, is the best way to find a bad glow plug. But be sure
>> >to disconnect the feed plug
>>> > > first.
>>> > >
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--- In diesel_mercedes@yahoogroups.com, BStromsoe wrote:
>
> Bogy, this is worth posting in our permanent archives.
>
> Â
> brian from laverne, ca
> Mary (195K)Â Martha (280K)
> 1983 w123 300d's
>
>
> ________________________________
> From: Bogy Wan Kenobi
> To: diesel_mercedes@yahoogroups.com
> Sent: Tuesday, February 12, 2013 10:07 AM
> Subject: Re: [diesel_mercedes] Re: glow plug problem
>
>
> Â
> Let's see:
>
> Yes you should have pulled the plug before doing a resistance test. What you were testing is all the plugs together and if one is good then that is the one that you are testing. If, say, two of them have opened up, then the remaining three will still show a connection. You have to resistance test them individually. And even then a low resistance does not mean they will work. The only real way to test them is by measuring the current they use, and that has to be measured for each individual plug.
>
> Also, the fact that they are getting 12 volts does not mean that any current is flowing. It only means that the supply wire is intact. Remember that a disconnected battery shows 12 volts across it's open terminals. But there is still no current flowing. 12 volts at an open glow plug doesn't tell you anything useful.
>
> By the way, most electrical problems are not short circuits, or shorts. Most electrical problems are open circuits. That's when the wire breaks, or the transistor stops conducting, or the light bulb filament breaks, and no current flows. This is how glow plugs commonly fail. They burn out and open up. They get too hot and the resistance element inside them melts or evaporates or fizzles away and opens up. In the rare case that they melt and "short", the fuse would blow from too much current flowing.
>
> When all the plugs are working, you can turn the key on with the door open and watch the dome light dim down a bit. This is because they will pull enough current to materially affect the battery voltage, and the light will dim down a bit. Then, when the relay turns off (opens the circuit) the dome light will get a little brighter. Now one glow plug may or may not have this effect. But if it does then that is an indication that it is pulling current and may be good. Again, the only real way to tell for sure is with a current measuring meter.
>
> So here is a simple and uncalibrated way to measure current: get a small (1 inch or so) and relatively weak bar magnet and "attach a thread to each end". I put that in quotes because you can tape the middle of a long (24" or so) piece of thread to the magnet. Hang the magnet by the two threads, forming the shape of the letter "V". Hold it over the wire under test, at 90 degrees to the wire, and one inch above the wire. Then have a friend turn the key. The magnet will want to align with the wire if current is flowing. The more current flowing, the stronger it will 'snap' into alignment with the wire. This is how large DC ammeters are made. Except that they attach the magnet to a spring and an indicator needle. But you should be able to tell the difference between good glow plugs and bad ones by the difference in response.
>
> Otherwise, you could pull them all out and energize them to see if they get hot. It is actually fun to watch. Or you could turn the key on when the engine is cold and touch a crayon or candle to the exposed end to see if they have gotten hot. (CAUTION: BURN WARNING! TRY AT YOUR OWN RISK!) The good ones will get hot and melt the candle.
>
> Okay, here is one more possibility. Unplug the bigger glow plug wire plug at the relay. Then you could touch a hot wire from the battery to each individual glow plug, one at a time, and observe the size of the spark produced. Weak sparks mean low current and bad plugs.
>
> But unscrewing each plug is the most sure way for the novice to test his glow plugs.
>
> That's it. I'm out of tricks.
>
> Bogy.
>
Thank you, Bogey. I will mess with it again tomorrow. It is supposed to be nice weather-wise again, so iI can work on it.
I will keep you posted.
Sid
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Boyd (410)592-5857
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This suggestion sounds really good. But it works way better when the guy who says he has one of those thermometers hasn't forgotten where he put it for 'safe keeping'. In a message dated 2/12/2013 2:15:09 P.M. Pacific Standard Time, vwnate1@yahoo.com writes: Another quick & dirty way is to buy a $20 Infra Red Thermometer from Harbor Freight and shine it at the base of each glow plug where it screws into the cylinder head , as the relay is on , engine cold ~ this way NO BURNS (it cannot be overstressed how badly a Glow Plug will burn you !!) , if the thermometer shows a lot of heat , shine it on the next glow plug , when you find some that are not blistering hot , those are the bad ones .
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To - day I drove SWMBO's '84 European 300TD to work and my Boss , who is German , ran out to look at it along with some of the guys ~ they all raved about how pristine and nice it is , here I'm still grumbling about the body works I had done .
One thing for sure , it goes like a scalded cat and I don't even need to give it over 1/4 throttle .
It'sa nice car to be sure but I can tell at a glance it's had body works done and that doesn't sit well with me .
I dislike " Mechanic's marks " of any kind .
-Nate
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This is all very good .
Another quick & dirty way is to buy a $20 Infra Red Thermometer from Harbor Freight and shine it at the base of each glow plug where it screws into the cylinder head , as the relay is on , engine cold ~ this way NO BURNS (it cannot be overstressed how badly a Glow Plug will burn you !!) , if the thermometer shows a lot of heat , shine it on the next glow plug , when you find some that are not blistering hot , those are the bad ones .
For the labor involved I prefer to change them all at once .
Monark brand gets the nod over the current Bosch crap ones .
Always , _ALWAYS_ use a closed end wrench to loosen them , I think a ratcheting box end wrench is prolly the easiet way to do them .
-Nate
Bogy wrote :
>
> Let's see:
>
> Yes you should have pulled the plug before doing a resistance test. What you were testing is all the plugs together and if one is good then that is the one that you are testing. If, say, two of them have opened up, then the remaining three will still show a connection. You have to resistance test them individually. And even then a low resistance does not mean they will work. The only real way to test them is by measuring the current they use, and that has to be measured for each individual plug.
>
> Also, the fact that they are getting 12 volts does not mean that any current is flowing. It only means that the supply wire is intact. Remember that a disconnected battery shows 12 volts across it's open terminals. But there is still no current flowing. 12 volts at an open glow plug doesn't tell you anything useful.
>
> By the way, most electrical problems are not short circuits, or shorts. Most electrical problems are open circuits. That's when the wire breaks, or the transistor stops conducting, or the light bulb filament breaks, and no current flows. This is how glow plugs commonly fail. They burn out and open up. They get too hot and the resistance element inside them melts or evaporates or fizzles away and opens up. In the rare case that they melt and "short", the fuse would blow from too much current flowing.
>
> When all the plugs are working, you can turn the key on with the door open and watch the dome light dim down a bit. This is because they will pull enough current to materially affect the battery voltage, and the light will dim down a bit. Then, when the relay turns off (opens the circuit) the dome light will get a little brighter. Now one glow plug may or may not have this effect. But if it does then that is an indication that it is pulling current and may be good. Again, the only real way to tell for sure is with a current measuring meter.
>
> So here is a simple and uncalibrated way to measure current: get a small (1 inch or so) and relatively weak bar magnet and "attach a thread to each end". I put that in quotes because you can tape the middle of a long (24" or so) piece of thread to the magnet. Hang the magnet by the two threads, forming the shape of the letter "V". Hold it over the wire under test, at 90 degrees to the wire, and one inch above the wire. Then have a friend turn the key. The magnet will want to align with the wire if current is flowing. The more current flowing, the stronger it will 'snap' into alignment with the wire. This is how large DC ammeters are made. Except that they attach the magnet to a spring and an indicator needle. But you should be able to tell the difference between good glow plugs and bad ones by the difference in response.
>
> Otherwise, you could pull them all out and energize them to see if they get hot. It is actually fun to watch. Or you could turn the key on when the engine is cold and touch a crayon or candle to the exposed end to see if they have gotten hot. (CAUTION: BURN WARNING! TRY AT YOUR OWN RISK!) The good ones will get hot and melt the candle.
>
> Okay, here is one more possibility. Unplug the bigger glow plug wire plug at the relay. Then you could touch a hot wire from the battery to each individual glow plug, one at a time, and observe the size of the spark produced. Weak sparks mean low current and bad plugs.
>
> But unscrewing each plug is the most sure way for the novice to test his glow plugs.
>
> That's it. I'm out of tricks.
>
> Bogy.
>
>
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Brian ;
I was very lucky in that I grew up at the knee of some really good older Journeyman Mechanics , I wish I knew 1/4 what they knew .
When I began my trade as a VW mechanic , I already had much experiance re awakening old junk from the fields , fixing things far from the barn and of course , normal kids tinkering of the 1960's , several of the Mechanics I learned VW's from were old Germans and they were really keen on repairing instead of total rebuilding every time like Most Americans do .
I took thier methods and applied them to the old junk we'd buy or drag in and learned how to properly evalute used engines and bits , trannies etc. too , when I went out on my own I began buying dead engine vehicles and patching the engines in each and every one so everything worked and they didn't leak oil ~ I've never had even one come back .
I never did patch work for Customers as I didn't want to warranty those jobs .
When I'd sell the used , patched vehicles I was often asked " is this engine rebuilt ? " after they'd look under the hood and see it all shiny and nice , no oil drips , no frayed wires , no missing parts, bolts , brackets or whatever and running as good as new .
I _always_ said " no , I didn't rebuild it " and often they'd think they got one over on me .
I'd tell the customer in this case to maybe enroll in the local Night School mechanics Class and be ready to spend some time on it , it'd be a great cklass project to patch it back to robust health.
Oe of my multiple mottos is " practice your craft on the junk , then when it's important you'll do a better job ".
Yes , it's always time & $ in the end , as I don't mind the hours spent ,the $ is vastly reduced my way and typically more reliable .
-Nate
Brian Stromsoe wrote:
>
> These thoughts went through my head when I seized my engine (hole poked in pan). I just felt that if the pistons seized, then maybe the crank seized too, or the valves had issues, or you name it. So, I just chickened out and went for a used engine transplant. And considered a rebuilt new engine too. It's all matter of time and money, isn't it? What would you advise an owner if he pulled into your shop with your sob story?
>
>
>
> brian
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| I don't know how to do that. :( But if you know how then feel free to copy and paste as needed to post it. Glad it's worthy. Bogy. --- On Tue, 2/12/13, BStromsoe <bstromsoe@yahoo.com> wrote:
|
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