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  #1  
Old 02-13-2010, 09:33 PM
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124 '87 300TD ABS pulse or power steering problem?

This could be a Tom and Ray "puzzler" for all 124 experts. So here's what's happening. Morning/cold engine start, and turn the steering to the right to back out - the car shudder/pulses like the ABS brakes are grabbing - but I don't really feel the car stopping. Straighten out the wheel and it goes away. Drive straight and it's OK (accelerating) but take a right turn and I feel the pulse again (throught the steering wheel), my foot is off the acceleator, but not on the brake. It is a rythmic pulse, 2-3 per second until I straighten out. Happens if foot is not on the accelerator. Accelerator is the cure!

Pulse is less after car warms up. But sometimes it pulses when going straight. Again, accelerator is the cure.

Per advice on this forum and from MB dealer mechanics, I've changed out the problematic ABS sensors (from the caliper/throug the firewall to the connector on each side) to both front wheels TWICE. Granted they were from junkers, but nothing has changed (more or less pulse) with 3 pairs of good looking ABS sensor cables (for $ale if you need a pair). I've checked the sensor in the rear dif. It also looks good and I can't imagine how it has anything to do with turning the wheel to the right. This has been going on for too long and needs to get fixed. It is starting to sound like a power steering pump problem! Fluids level looks good. 290K on engine (new head gasket, and rebuilt turbo, and spruced up #22 head has it screaming (thanks so much to Sixto), as much as a 6 cyl screams).. but this pulse ... It's got to go! Any ideas, recommendations, suggestions, words-o-wizdom?

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  #2  
Old 02-13-2010, 10:35 PM
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Does sound like the P/s pump, or, something binding up at the steering joints. Have they been greased? Especially if you say it gets better when warm. Before replacing the pump, might try to flush the P/S fluid with fresh and see if that helps.
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1987 300TD 147,000 miles- Palomino leather interior, 1995 facelift and body cladding, E350 wheels, Rebuilt suspension and sport springs, rebuilt turbo, New Monarch injection pump and injectors....and the list goes on and on...
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Old 02-13-2010, 11:58 PM
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Yeah, I just got back from an evening run, and all I could think was its the p/s. This is after months of being told/believing/knowing it was the ABS. Except that the parts replacements didn't fix it (damn those bad used parts!) Can't wait to sus out the p/s.

By the way - nice looking white wagon! Is it running yet? What does it need? Mine is white, too, and with tinted windows it's a comfortable combination through the heat of summer. I'm on my #2. First was yellow and had only 178k, but this is significantly "cleaner". FYI, I suspect that at 290k mine is on the 3rd headgasket. It has a #22 head, which I don't think came stock, and just "needed" another headgasket. But now it is done, and when this p/s-or-ABS pulse goes away, I'll be down to complaining about the stuff that doesn't really matter.
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Old 02-14-2010, 02:20 PM
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I 've had mine for a month now and still trying to get it running between work and family. Here is the Thread if you really want to know Starting issues 87 300TDT- injection pump or anti-theft??
By this week, I will know if it is fuel issue or compression issue.

The #22 head is not factory (the #14 was) and is the best replacement head you can get. That alone is worth a pretty penny.
Mine is in good condition with leather, but I hope to really transform this car once I get it running right.... 1995 updated front-end, newer MB wheels. Clean and tasteful.

It is a rear breed these wagons!
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1987 300TD 147,000 miles- Palomino leather interior, 1995 facelift and body cladding, E350 wheels, Rebuilt suspension and sport springs, rebuilt turbo, New Monarch injection pump and injectors....and the list goes on and on...
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  #5  
Old 02-14-2010, 03:51 PM
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I have never had my wagon P/S pulse.. but have you checked the fluid level (i'm sure you have but have to ask) also have you looked at the filter? someone I think said my wagon had a filter in the bottom of the cup in the fluid. something to look at perhaps
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  #6  
Old 02-15-2010, 12:16 AM
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I started to give advise on the ABS system, but after re-reading your initial clues, I think it may well be a bad PS pump. The pulsing is fast ith ABS system activated, its like a Brrrrrt!. maybe 20 pps, you say you feel only a few pps (pulses per sec). You do NOT feel anything in the brake pedal when it pulses, right?
If so that sounds like the pump to me, based on when you accelerate slightly it goes away.
FWIW, the wagon uses a special pump also, as it has a separate SLS pump incorporated in it. Finding one is not going to be easy and the dealer will want a carload of cash for a new one but put a want out on the parts section and I'll bet a member comes up with something.
This is a strange thing I've never encountered before though. I have a bad SLS servo on my wife's '87 300D and it is not sensitive to acceleration, it likes to pulse just as the car slows to a stop while braking (brrrrt! sound and you feel the pulsing in the brake pedal. Never does it with no brakes applied.
DDH
PS yes there is a filter at the bottom of the PS fluid reservoir, worth changing along with the correct fluid. Probably hasn' been changed in years unless PO was really up on their maintenance.
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Old 02-15-2010, 08:17 AM
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Any credibility I had as a home mechanic is shot. It was the p/s fluid level. Found a slow line leak from a loose philips screw clamp. I'd emptied the last of a can a few months back (before rebuilding the head/replacing the headgasket). Not sure the last of the can made it up to the MIN-line on dip stick. Anyway, even though there is a lot still of fluid in the tank, the level was below the dip stick MIN.

DDH, thanks for the info on the ps pump. As this has been going on for a while, I may need a pump someday. Do you know if the 300TE gasser waggons have the same ps pump? What is the SLS?
And yes to the symptoms, it was not "Brrrrt", it was 2-3/sec. I felt it mostly in the wheel, and passengers could feel it. It pulsed at slower speeds, close to idle or coasting into a turn at low RPMs, worse when not warmed up. I did feel it in the brake pedal, so I tried not using the brake and coasting, or accelerating into turns. Pulse was mostly notable on Right turns which is the symptom that indicated the "commom 124 worn ABS wire problem". And yesterday when fluid was lowest, it also pulsed going straight. This was less than a week after I replaced the 2nd pair of ABS sensors. You were right to diagnose the 2-3/sec vs the brrrrt.

Aquaticedge, Thanks for the heads up on the filter. The ps pump looks awfully clean on this engine, and I didn't clean it or replace it, so I'm guessing PO did (the leaky line culprit). I think I'll just run it a while, and see how it feels. And i'll put the filter/fluid change on a future (deferred) maintenance list

1stnc, I feel for you. The length of you diagnosis is painfully reminiscent of what I went through to diagnose my headgasket problem. Congratulations of finding you need new glow plugs. That may fix a lot of your start problem. Good luck with the compression test. FYI Be carefully with the socket wrench removing and reinstalling the injectors. It's easy to bend the small ports on the sides of the injectors. They can get bent in too close to the injector for remounting the return line (some of mine bent in, and I prayerfully pried them back out.) And be sure to turn the engine over enough times to get a good reading.

You'll have a chance to inspect, clean, air-out, each injector for crapage. You said you replaced the woven fuel lines on the injector ports, blow them out onto a kleenex to see if any particles are in the new lines. And you could remove the hard lines from the IP and blow those lines out, too. Who knows what you'll find in them? How do your filters look now? Any rust particles? Any particulate in the bottom of your Diesel Kleen bottle?

I'm inclined to go with others on your thread who point at your really dirty fuel That is a problem. The fuel lines have to run clean. Emptying the tank, cleaning the fuel system, replacling the new filters again, and new glow plugs could do it for you. (k.i.s.s.)

I don't remember seeing that you looked into your injector pump for rust particles, just that you removed some hard lines, and wanted to replace the IP. On my previous 87 wagon I'd replaced just my pump's rubber O-rings (2 x 6), and cleaned the pump following a DIY on this site. I have the splined socket tool if you need to borrow one. But I think you'll want to get rid of the fuel you have first. Especially if your tank is the source of the rust particles, and the particles are getting through your filters, it may be the belly of the beast you're fighting. Some guys posted about biodiesel being hard on the rubber. I only ran 2 tanks of 1/2 bio and 1/2 dino, and I had to rebuild my ip because it started leaking (worse) from O-ring deterioration. Was the O-ring deterioration caused by the bio? Lots of people say it is. And lots of those same folks are saying bio "cleanses" the rust from your tank. I didn't notice any rust problems from my brief flirt with bio, just fuel leakage.

I'd do all I can to be sure the fuel lines are clear before "fixing" the cat. And I'm speaking as one who has done the cat, since I had the exhaust off to do the head. I didn't notice a change in exhaust improvement. Working around under there is a PITA. You may want to leave the ex-manifold plug off for a while to simulate a fixed cat.

Hey wait, don't pay attention to any of this. I just remembered: I don't have any mechanical cred. So it probably is the cat!

Good Luck.

Last edited by johnscars; 02-15-2010 at 01:45 PM.
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  #8  
Old 02-16-2010, 09:23 PM
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Johnscars, its good to hear the problem was, well simple, and we all overlook the simplest things from time to time.
SLS is Self Leveling Suspension
Yes gasser wagons use the same pump, in case you ever need one.
DDH
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  #9  
Old 02-16-2010, 11:24 PM
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Sometimes the simple things get us .

I posted some result on compression - all good. Working on the new fuel lines now and cleaning. I will look for the DIY to clean the IP. THANKS!

I've by-passed the fuel tank completely as the tank will need to be professionally cleaned out.
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1987 300TD 147,000 miles- Palomino leather interior, 1995 facelift and body cladding, E350 wheels, Rebuilt suspension and sport springs, rebuilt turbo, New Monarch injection pump and injectors....and the list goes on and on...
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  #10  
Old 02-17-2010, 10:34 AM
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Celebrated too soon. It probably needs a p/s pump. The pulse is still there, especially at low revs turning right when cold in the AM. I have a p/s filter that I got for my previous wagon, but never installed. But with the price of hydro-fluid, and the fact that these pumps wear out, I may save the filter for the next pump. Any rebuilders or rebuild kits out there?
Any leads on a used pump?

DDH and 1stbenznc, your cat diagnosis reminded me that I've seen the same low-revs-only, and engine-dies symptoms on 3-4 Ford fleet vans when they need a cat. And replacing the clogged cat cured the symptoms. But I'll be hoping that just cleaning and tightening your fuel lines does the trick.

Last edited by johnscars; 02-17-2010 at 11:11 AM.
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  #11  
Old 02-23-2010, 09:53 AM
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Pulse still there, especially at low revs and in reverse. On the advice of a Napa mechanic I replaced the brake booster vacuum line with the black and white check valve, as mine looked decayed and I suspected was restricted at low vac, then I broke off the "T" to the small rubber vac line. Anyway, no change to symptom.

So lets blow this open. STEERING BOX?
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  #12  
Old 02-23-2010, 10:35 AM
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Does this describe what you feel. If your turning the wheel slowly to the right and then back to the left quickly do you feel a "dead" spot or a breif lack of power assist? If you feel this symtom that is air traped in the gearbox and will drive out. This system creates its pressure based on volume, if you are loosing volume due to an internal (bypassing back to the return) leak most the time it is described as a whine or viabration from the pump, not a pulse. I hate to see you replace the gearbox and be in the same boat. I'm happy to answer any questions you may have, if you like give me a call. 702.734.8090

Chris
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Old 03-02-2010, 03:59 AM
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Chris, thankfully there is no dead spot and no whine. And I'm hoping that isn't the issue. I had a chance to stop by Sun Valley MB Dismantlers on my way through LA last Friday. They diagnosed it as bad motor mounts and showed me that the engine moved R-L alot, and probably caused the low rev feeling when cold (it deminishes when warmed up). With luck, I'll have the new ones in by next week. I didn't get the tranny mount, and will see how these work first. PS - I appreciate that SVMD didn't diagnose it as something they could sell me, and instead they told me how to do the repair.
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  #14  
Old 03-20-2010, 05:26 PM
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Yes it was the motor mounts. It is pretty amazing to have all of the symptoms gone, and the car just drive normally. thanks for the guidance and diagnostic help.

I just wish I'd changed them when I was redoing the headgasket.

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