Help Deer Problems 1972-108-450 Will Not Start - PeachParts Mercedes-Benz Forum

jim16671836 · #1 10-02-2010, 01:43 PM

I have a 1972-450 that will not start or run. The coil wire has spark, the sparkplugs have spark. I disconnected the fuel lines at the fuel rails and both sides have pressure. I trird to start the engine a number of times and then I pulled 2 spark plugs and they are dry. When I try to start the engine it turns over good and once in a while makes some slight poping noises. I have removed the air cleaner assembly. Does that make any difference. The car hit a large deer going about 70mph on the Interstate on the front passenger side. Destroyed the right front fender, right headlight, right fog light, hood, grill, radiator, condensor, aux. fan, engine fan and the radiator cradle from the right side fender clear over near the left fender. A electronic item that might be a computer that is almost behind the right side fog light was pushed back about 3 inches. Their is also a electronic device on the front left side almost behind the left side fog light. It was also moved a couple inches. If it is onr of these devices can I take them apart and check for damage??? Any help will be appreciated. As soon as we put the final coat of 158(white-gray) paint on and reinstall a grill it will look almost like a new car.. Jim

Tomguy · #2 10-02-2010, 02:23 PM

The two devices are the ECU brainbox (the one that was on the passenger front side, on the car's right of the radiator or left if viewed from under the hood). The other is the ignition box. Either or both could be dead but I'd put my money on a cracked ECU board. You say the plugs are dry with an occasional pop so it's probably dead aside from the cold-start valve on a separate thermo-time switch that will eventually give enough gas for a small pop.

You can take it apart & resolder the cracked board if you're daring, or search eBay or a dismantler for a cheap used box. You say 108 450, you mean a 280SE or 280SEL 4.5? Box should be the same on all 108 & 109 w/the 4.5 as well as all 107 and 116 D-Jet boxes (450SL, 450SLC, 450SE and 450SEL from 1971 to 1974) will also work, may not be DIRECT replacements p/n wise but direct plug-and-play.

jackson101 · #3 10-02-2010, 02:25 PM

Jim,
Did you try a little fuel or a shot of either down the intake?
Did the car stop running immediately after hitting the deer?
Did the car run after hitting the deer, then refuse to re-start after?

Mr.Kenny · #4 10-02-2010, 08:59 PM

Quote:

Originally Posted by jackson101

Jim,
Did you try a little fuel or a shot of either down the intake?
Did the car stop running immediately after hitting the deer?
Did the car run after hitting the deer, then refuse to re-start after?

ALSO; Did the deer keep running after the hit?

jackson101 · #5 10-05-2010, 01:11 PM

Quote:

Originally Posted by Mr.Kenny

ALSO; Did the deer keep running after the hit?

Yes, very important.

jim16671836 · #6 10-05-2010, 03:57 PM

I want to thank everyone for their input. We tried a little gas but nothing really happened. Deer was dead immediately. I don't know if the engine was tried to restart or not. I will check into that... We pulled the ECU Brain and it looks like a hot spot about a inch long maybe but cannot be really sure. Just discolored and could find no crack in either board.. Going to pull the ignition box and check it.. Also buying a mirror to see if the pickup is still in place down by the harmonic balancer... That has nothing to do with setting the timing, correct.. That function is done by rotating the distributor. The distributor has the trigger points in the lower half of the distributor. Jiim

Tomguy · #7 10-06-2010, 10:09 AM

The ECU is fed by those points. There is no crank or cam position sensor for this electronic ignition setup. If the board has a black spot it's probably fried.
http://notadomain.net/misc/Benz/2004-04-24/DSCF0051.JPG

jim16671836 · #8 10-06-2010, 08:56 PM

Thank you for your knowledge... I wonder where I can find another ECU in good condition. Hopefully I can find someone that wants to trade for other parts.. I found another ignition box today but it is from a 1969-280SE. Will pull the ignition box tomorrow and open it and check it... I don't know where or who can test the 2 original modules. So it is probably a lot easier on the pocket book to find a couple used modules... Any thoughts or ideas... Jim

GaryF · #9 10-07-2010, 05:42 AM

Quote:

Originally Posted by jim16671836

Thank you for your knowledge... I wonder where I can find another ECU in good condition. Hopefully I can find someone that wants to trade for other parts.. I found another ignition box today but it is from a 1969-280SE. Will pull the ignition box tomorrow and open it and check it... I don't know where or who can test the 2 original modules. So it is probably a lot easier on the pocket book to find a couple used modules... Any thoughts or ideas... Jim

The ignition box is the easy bit, either bypass it temporarily to get the car running again and get a crane or pertronix replacement for the long haul. Lots of stuff in this forum about the conversion.
The original ignition box might look and test ok on the bench but have issues when it gets hot in regular use.