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 TE issues (aka, the dog)
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WA6VQP

USA
161 Posts

Posted - 02/11/2019 :  17:30:31  Show Profile
Hello all!

OK, this is totally not an M-100 question, but you folks all have way to much experience with the MB marque for me not to try...

As I may have mentioned previously, I picked up an '88 TE in pretty nice shape, body wise, with some electrical issues and lack of maintenance, for a mere $300. Right away I nicknamed it "the dog."

Anyway, I got it home, got it new tires and battery, and thought it would work well enough to drive it to where I needed to get it fixed up.

I was wrong.

So, driving it to town, it died. At first the engine ran OK, but hesitated at moderate (30-40 MPH) speeds. The it just up and died. Got it towed home, and finally got to putzing with it this past weekend. When I try starting it, it cranks, tries to fire, and sometimes seems to backfire a bit, but no joy.

I checked fuel flow to the fuel distributor. Lots of gas there, so fuel pump and filter seem OK.

A curious thing, however: After trying to start the car, the headlights and front running lights flash for about a minute, then stop. The battery is definitely OK (it's new, and I've measured the voltage, all is well). I'm thinking that somehow this might be related, though for the life of me I cannot say why.

Any ideas???

Thanks!

Jim



1979 450SEL 6.9 (Black/Safran)
1987 560SL (Red/Palomino)
and now, 1988 300TE (White/Tan)

Driven with "old man" sheepskin covers!

FEMA

USA
1400 Posts

Posted - 02/11/2019 :  21:34:04  Show Profile
Jim, so right now the car just starts and dies as you described? Are there any other symptoms you can think of?

Francis E. Abate
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ctmaher

USA
694 Posts

Posted - 02/11/2019 :  21:55:06  Show Profile
Crank sensor? That would explain the no start, but the lights issue, not so sure it's related, unless you have a power supply issue.

Chris
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WA6VQP

USA
161 Posts

Posted - 02/12/2019 :  12:13:42  Show Profile
Thanks for the replies...

OK, I unhooked the box that was clicking, and it says "Becker" on it. I'm guessing it might be some kind of alarm module. I'm going to check it out and see what I can find. The radio in the car is gone, so it may be that the alarm module is responding to that. Who can say? Nonetheless, I suspect this has nothing to do with the engine issues.

Chris: Thanks for the tip on the crank sensor. Anyone know how to verify whether that works correctly without simply replacing it? How hard is it to get to?

I'm going to spend some time later combing the InterWeb for schematics and service info. I'll keep everyone posted as I progress.

The dog shall live again!

Regards,
Jim


1979 450SEL 6.9 (Black/Safran)
1987 560SL (Red/Palomino)
and now, 1988 300TE (White/Tan)

Driven with "old man" sheepskin covers!
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ctmaher

USA
694 Posts

Posted - 02/12/2019 :  21:40:48  Show Profile
Jim, the Becker module is in fact the anti theft alarm module. That is most likely what is causing your flashing lights issue. They were prone to getting flaky and causing false activations....usually one of the door lock switches would be the culprit, but most folks simply unplugged the module.

The crank sensor should not be too hard to replace on an M103 compared to a V8, it's at the rear left of the engine where the transmission bellhousing meets the engine. Best way to test would be with a scope, as it generates an AC sine wave. You can test resistance at the connector that plugs into EZL, I believe it should be about 800 ohms. They tend to fail with heat, so on a cold engine they work, and after it warms up they fail. Very common failure item, I'd be 90% certain that is your problem. The other part that can fail and cause a stall like that is a bad fuel pump relay, but sounds like you are getting good fuel supply.

Chris
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Ron B

Australia
11659 Posts

Posted - 02/13/2019 :  04:43:08  Show Profile  Visit Ron B's Homepage
Hmmm... OK, it was running ,then stopped. The alarm module is working as it should so that is not your problem. Make sure you have at least 11.9 Volts to the main connector from the battery. Check that it's clean. Is the fuel pump working? A dud relay is such a common problem that to get the car going it's a simple matter to remove the relay,connect terminal 87 to 50 with a piece of wire and you should here the pump run. If it's not running,replace it and the filter. try again
If the pumps running the car should start. ( if this car has sat around for a while,I am picking it's the old pump, dirty filter and old fuel scenario)

Check for adequate spark by pulling a lead,stick a plug into it and crank the engine over. it should click audibly as the spark jumps.
If not,remove the distributor cover and see how much oil has leaked into there .
They all leak and eventually you lose spark and the rotor arcs out and gets burnt.
That's a few things to get a M103 running .

Edited by - Ron B on 02/13/2019 04:45:36
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mpmorris

USA
1387 Posts

Posted - 02/14/2019 :  10:54:37  Show Profile  Visit mpmorris's Homepage
Yes to the possible crank sensor -they are known to fail(the cable at the sensor is the common issue for open circuit- Also, you might remove the distributor cap and check the rotor mounting bracket --they are known to crack and fall off causing the car to sort of backfire and/or attempt to start as the cam will turn the rotor somewhat and have a cross fire.

On another note:

Recently, we installed a Genuine fuel pump relay for the 103 engine (new fuel pumps installed) -- it failed within 3 weeks -additionally, we installed a Genuine glow plug relay in a 126 SDL --it failed withing an hour (glow plug lamp did not illuminate with key on but would stay illuminated after start up -yes -glow plugs were ohm tested as ok) --After market relays are known to fail but we are now disappointed that even the Genuine parts are now suspect. --On another note: Mono-valve heater replacements are still of good quality as Genuine ($120.00 cost) -but all after market replacement diaphragms and valves are seriously flawed --the spring lift are weak/diaphragm is stiff so the flow is restricted or will not flow at all.

tech notes
mpm

Edited by - mpmorris on 02/14/2019 11:05:14
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Ron B

Australia
11659 Posts

Posted - 02/14/2019 :  18:34:54  Show Profile  Visit Ron B's Homepage
Are they getting the genny parts made in Guangzhou?
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Ron B

Australia
11659 Posts

Posted - 02/14/2019 :  18:38:04  Show Profile  Visit Ron B's Homepage
If it were an earlier version I would be checking the loom across the engine, the one inside the plastic boxing. That is well known as the place where the self destructing looms would fall apart,some getting so bad they burnt the car down. have a look anyway, if the insulation falls off as you rub the wires,it's time to re[pair or replace.
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ctmaher

USA
694 Posts

Posted - 02/15/2019 :  11:06:18  Show Profile
I would not suspect a wiring issue on a 1988 with K-jet. The decomposing wiring harness issue seems to be mainly with the cars that had the LH injection system...starting with the W140 in 1992 and ending in around 1997 when they finally changed the wiring harness materials. So that would be LH M119/M120/M104 for the most part.

Chris
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cth350

USA
1535 Posts

Posted - 02/18/2019 :  17:35:07  Show Profile  Visit cth350's Homepage
I had some fun with my '89 TE for a while.

The flaky ground wire to the coil was the hardest thing to find.

For the rest, I let the computer tell me some hints. Like the little duty cycle check, the flashing codes, that sort of thing. There are some decision trees in the M103 engine manual to work from and several basic internet posts.

You need a digital meter that can read duty cycle, the book and time to read it and maybe a wealth of spare parts to isolate faults like bad relays a faulty altitude sensor.

-CTH
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WA6VQP

USA
161 Posts

Posted - 02/18/2019 :  18:05:39  Show Profile
Hello all (again),

I had a few minutes between weather fronts this past weekend to do some sleuthing on the dog (AKA the 300TE). Since I realized the "clicking" module was the alarm system, I simply left that unplugged, thinking it might be messing with the engine, since it obviously thought that someone was trying to steal the car.

At first, no change. Then, after a few attempts, the engine fired and ran at idle quite nicely. However, when I tried revving the engine, it got rough, and revving it two or three times, it died, and I was back where I started.

This leads me to believe there is something intermittent, like the previously mentioned rotor bracket, or bad coil ground wire. I will check into both items when I get the next opportunity. I started loosening the distributor, but the weather was closing in, so that will have to wait until next time. The car is parked outside, and moving into the garage is not practical without a running motor, so that is the first order of business.

I will update as things progress! If anyone has more ideas, by all means post them! Thanks to all for the suggestions so far.

Best Regards,
Jim


1979 450SEL 6.9 (Black/Safran)
1987 560SL (Red/Palomino)
and now, 1988 300TE (White/Tan)

Driven with "old man" sheepskin covers!
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WA6VQP

USA
161 Posts

Posted - 03/13/2019 :  15:36:36  Show Profile
New developments in the dog saga...

After reading some of the advice here on the forum, I decided to pull the distributor. The rotor looks fine, as does the cap (sort of). There is, however, a round disk behind the rotor which looks damaged, and there is dust from that part coating the cap.

The pictures show the issue.

Any thoughts? Thanks!

Jim











1979 450SEL 6.9 (Black/Safran)
1987 560SL (Red/Palomino)
and now, 1988 300TE (White/Tan)

Driven with "old man" sheepskin covers!
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ctmaher

USA
694 Posts

Posted - 03/13/2019 :  23:58:57  Show Profile
Umm, where is the rotor?

Chris
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WA6VQP

USA
161 Posts

Posted - 03/14/2019 :  13:44:53  Show Profile
Chris,

I took the rotor off to check it. It was originally installed correctly, but I'm waiting to put it back on until I understand the wear I'm seeing a bit better.

Thanks,
Jim


1979 450SEL 6.9 (Black/Safran)
1987 560SL (Red/Palomino)
and now, 1988 300TE (White/Tan)

Driven with "old man" sheepskin covers!
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WA6VQP

USA
161 Posts

Posted - 03/19/2019 :  17:32:45  Show Profile
Well, after a quick back and forth with Tom at the Classic Center, I discovered a missing gasket in the distributor assembly. That's on order now, and when it comes in, I'll install it and see what happens.

However, I still think it's something else. The crank sensor is probably next.

I'll keep you all posted!

Regards,
Jim


1979 450SEL 6.9 (Black/Safran)
1987 560SL (Red/Palomino)
and now, 1988 300TE (White/Tan)

Driven with "old man" sheepskin covers!
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