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  #1  
Old 01-03-2020, 06:28 PM
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New to me 87 300sdl needs some things addressed

I just picked up this car for $300 basically to get my feet wet on the next generation 6 cyl engines and at the very least have a core pump to send to diesel pump UK when it's big power time. The previous owner was a young kid that didn't really know a lot about cars. He had it for a while I guess drove it through the summer I'm assuming and the battery died and he couldnt get it to start. So I bought it hoping it was something stupid and I could get it running. I drove 300 miles to pick the car up so it wasn't like I was going to turn it down for three hundred bucks when I found a little oil on top of the coolant in the reservoir. He claims that somebody poured it in there by accident but I find that fairly unlikely. I've got no exhaust pressure in the cooling system and no coolant in the oil so that's a plus. But after doing some research I found I have the dreaded 14 casting head, so I guess it's possible there's a crack in there and it's seeping a little oil. I'll cross that bridge when I get to it if it's a problem, the starting issue was dead battery and four bad glow plugs. It started after a torpedo heater got it up over 40. It runs good and seems pretty healthy power wise. I fear they have been bad for quite a while and I've read about how it can be a problem getting the glow plugs out if they have been not operating for an extended period. I want to get it drivable 2 figure out the health of the engine. the chassis is so-so at best it's got the big rust holes under the sway bars in the front, lots of horrible Bondo work too. It seems to drive okay though as far as the probably 55 miles an hour I got it up to down the street from my shop.

So first dilemma is the glow plugs. It certainly looks like the intake has to come off, yay. so should I crack the glow plugs loose a little bit and soak them in penetrating oil for days or whatever before I try to unscrew them all the way? Any other tricks to try to avoid breaking them off? The plugs are getting power but no wait to start light. No continuity on 4 of them. My understanding is this system will not light it if there are, what? One or more bad plugs?

Second is the tachometer is not working. I pulled the ovp relay and the fuse is good and when I did the idle dropped so I'm thinking that that is working okay. I don't know if the tach function could be separate internally from those functions. Diseasel 300 mention the EDS(?) which I have not had a chance to really look into very much but I guess that's probably one of my next courses of action.
I just haven't had time to look deep into it yet. Or it's the cluster/tach itself. Would a 300se cluster work(I figure not but there is one floating around)I'm also wondering how the ovp and pump is electronically controlling the idle? I was under the impression it's fully mechanical and this (or whats left of this) drivetrain is not destined to remain in this car.

I am a little concerned about the oil in the coolant so it will get a good flush and cleanse to see if it returns. I really doubt I'll replace the head if it is an issue, I'll just be looking for an OM606 to take its place. That was the end goal anyway and after finding out about the head issues definitely going mechanical pump 606. The drivetrain will be 5 speed OD manual and LSD 3.27 in my w123 wagon or posiibly a fintail or w108.

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Last edited by rwd4evr; 01-03-2020 at 06:47 PM.
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  #2  
Old 01-03-2020, 07:28 PM
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Oil in coolant would likely be from a head gasket breach, not a cracked head. Cracked head will result in pressurizing of the cooling system and overheating problems.

If you're careful, you can do the glow plugs without removing the intake manifold, but it's a big PITA. A spherical swivel joint and a GOOD set of ball-end allen bits is your best friend getting the allen screws out. The glow plugs will probably come right out. Unless everything in the engine bay is heavy with crusty corrosion, you probably won't even need penetrating oil.

Since the idle speed drops when you unplug the OVP relay, the EDS computer is functional. There is a solenoid on the back of the IP that controls base idle speed, think of it like the A/C solenoid on carbureted cars. You can set the idle mechanically if you're doing away with the EDS system with the screw directly above the idle solenoid on the IP. The most likely issue with the tach is the tach itself. It's specific to the 603 powered cars, so no gas tach will work. Most likely it has a bad ground connection on the back of the cluster (the metal bar across the back of the speedo is a ground link and gets oxidized) or the capacitors on the tach itself may be bad. Start basic.
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Old 01-03-2020, 11:31 PM
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Pretty rare that it's a one way no coolant in the oil on a headgasket, anything is possible I suppose. Maybe turbo seals? It definitely isn't pressurizing the cooling system so far at least. It sat and idled for over a half hour. Or maybe just some idiot pouring oil in the rad cap.

The other thing I forgot about is the box directly behind the IP. It's the mount for the throttle linkage pivots and Bowden cable, and it has throttle ball linkage back towards the block kind between the engine and IP. It hooks to a 8 pin on the fender well and has a big two wire (I think) plug on it, with the side squeezers. If I hook up that 8 pin it starts clicking and grinding as soon as key on and doesn't stop. I think its cruise control maybe?

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  #4  
Old 01-03-2020, 11:36 PM
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Cracked heads leak combustion gas into the coolant, not oil. The only way for oil and coolant to mix is to have a breached head gasket or some idiot dumping oil in there. If the latter, you should try selling them blinker fluid. They'd prolly buy it.

The box behind the IP is the cruise control servo. The box is the same for most 80s Benzes gas or diesel. The control amplifier is up under the dash above the brake pedal. If you aren't using CC, just leave it disconnected. If you want to fix it, contact forum member "James Dean", he does CC repair and does a good job at it.
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  #5  
Old 01-03-2020, 11:44 PM
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Cool thanks. I do love cruise control though.

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  #6  
Old 01-04-2020, 07:12 PM
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Rock Auto has Bosch 80006 glow plugs listed for om603 87sdl and om617 85 300sd. Then they also list a Bosch 0250201039 that says "part number 80007,80008" but only for the 603. The other brands seem to agree on the same for either but I'm not puting anything but Bosh in it. 80006 is half the price of the 80007, 80008, what gives? I also have 5 new in a 617 na motor that never ran so......

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  #7  
Old 01-05-2020, 03:28 PM
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Some of the 60x engines have afterglow relays (you’ll find contrary opinions, they’re wrong.) Afterglow requires a different plug, regular plugs would burn out more quickly. My feeling is that anyone attempting to replace plugs in a 60x without pulling the manifold is a bit daft. And pulling the manifold gives you an opportunity to clean out the gunk, which will be epic if it hasn’t been done before.

Is u you our AC functional? AC, idle control, tach, transmission lockdown, EGR, and antilock all interact. Think twice about messing with them.
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  #8  
Old 01-05-2020, 03:40 PM
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Afterglow showed up in the W126 in the 1990 model year. All '86/87 cars have the non-afterglow relay unless an afterglow model was retrofitted later in life. The prechamber and glow plug, even the injector is the same as late-model OM617's.
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  #9  
Old 01-05-2020, 08:23 PM
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Well, AC is not charged as of now. If antilock works I'll disable it as soon as it interferes once prematurely. I can do a better job 99% of the time. Sometimes you want to lock up tires(please let's not argue about this). Any reason not to block off EGR(that probably doesn't work right anyway).Are you saying trans kickdown is related to all these things? Worst case I can adjust idle manually I'm told. Are they all EDS related? My EdS seems to be operational. Hopefully it's a loose connection or something in the cluster.

Looking at it, I'm just taking the manifold off. I've played the "leave it on and go around it game" usually is a waste of time or at least aggravation. Cleaning it out is a good idea too I'm sure. May have my neighbor weld on a bung in the opposite side for intercooler install later too.

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  #10  
Old 01-05-2020, 11:10 PM
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The ABS is pretty forgiving on these cars. Unless there's a fault or you're driving like a moron, it'll probably never trigger.

EGR is your choice. Popular opinion is to delete the EGR. It's probably already mostly sooted shut anyway.

Trans kickdown is controlled by the KLIMA relay. It has a relay in there to inhibit kickdown when it decides to. The KLIMA gets it's RPM signal from the EDS computer. If there's an RPM output problem from the EDS, the KLIMA won't work which means no kickdown and no A/C. The KLIMA is notoriously flaky, so don't immediately assume an EDS problem.
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  #11  
Old 01-06-2020, 04:51 AM
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Yeah, I wouldn't say like a moron because I know exactly what I'm doing. but I do drive hard and throwing these big pigs around is good fun. I hate abs especially in the snow. Stiffened up a bit and manual trans(early 80's 280se) SLS delete and these cars are quite capable handling wise. My friend has a 500se that started pulsing the pedal just coming to a normal stop. I want no parts of a computer deciding that my brake input is a bad idea and it's going to override it. You or your wife or whomever may benefit from abs and I'm certain that it's saved many lives, but I am a driver, not a vehicle operator. I go drive cars around sideways as close as possible to my friends(on a track) for fun.

So is the Klima a Standard relay? I know we (fonzi and I) were swapping them around on his 500se(I think it was) from a couple different cars. I know there are quite a few floating around from various w126 and a couple 560sl parts cars I have. I haven't driven this thing around at all yet since the glow plugs are bad so I don't know if it kicks down nicely or what. I know on my 300sd it's got vacuum and Bowden cable control plus the stomp switch under the pedal. It's got lite to no vacuum right now and I personally like it much better. Besides having to let off considerably to get it to drop into 4th it's much nicer to drive without it upshifting so early all the time. But now I know I can reuse the never run glow plugs in my w108 280se 300d conversion parts car I should get some more Input from it. I bought it from an auction with a n/a om617 that someone had put in it but never changed the 4.08 rear. My best guess is it just got it's tounge hung out on the highway until it had no compression. It popped a couple times and blew a smoke ring out of the oil fill hole! As close to running as I ever got it. Its got brand new 3 year old glow plugs in it. Maybe heated a couple dozen times at most. I'll pick up a 6th or maybe just make sure I can get the 1 old one out easy. I guess I need intake gaskets so makes sense to grab another one while I'm at it.

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  #12  
Old 01-06-2020, 10:54 AM
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The Klima relay is right next to the OVP relay by the brake booster. Typically they have KLIMA spelled out on them. It's one of those combination relays that controls the A/C compressor cycling and the trans kick down. Why the trans is lumped in there, who knows.

The transmission is very similar to the one in the 300SD. Same setup and same family. If the Bowden cable is set properly you should get upshifts when laying on the kick down button ~4600RPM. Normal upshifts will be somewhere around 4200RPM. 1-2 will usually be somewhere around 3000-3500 RPM, it should get out of the way pretty quick. The vacuum only modulates shift hardness. If the modulator is adjusted properly and the VCV is aligned correctly, you should get a quick/firm shift but not so firm that it jerks the car. If it's shifting smooth/softly, it's wrong. You should notice an upshift, but it shouldn't be unpleasantly rough.
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Old 01-07-2020, 12:12 AM
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Yes I know what and where it is, I just didn't know if the Klima in every car is the same. As far as vaccum controlling shift firmness only, I think you are wrong there. My shifts started slowly getting higher and higher and I didn't mind (because I was down on power and needed it)but was curious. Then I finally figured out the vaccum pump took a **** when I had power brake issues.

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  #14  
Old 01-07-2020, 12:19 AM
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The bowden cable tension is what sets how high the RPM is when the shift takes place. The more tension on the cable, the higher RPM the shift takes place. The vacuum is "fudged" from the VCV to bleed off vacuum as the throttle is pressed. Think of it as feathering a clutch. If you pull off the vacuum line, the shift points will still be the same, they'll just all be at full firmness of whatever the modulator pressure is set at since there's no vacuum to soften the shift. There maybe a very small deviation in RPM, but the main actor is the bowden cable.

The Klima relay is specific to the diesels. The tach pulse is very different from the gas cars.

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