more more more 84 300CD problems - PeachParts Mercedes-Benz Forum

ivandrocco · #1 04-23-2011, 09:53 AM

Waiting on a new fan clutch because mine is seized-

However, my car runs hot, usually just under/over 100c.

Wouldn't the fan running all the time keep the car running cooler? Wondering if replacing the clutch is going to exacerbate the problem.

Also trying to diagnose low power. I've got okay power, feels good off the line- it's just lacking. Enough that the indy noticed it during a test drive, and tipped me off about the fan clutch possibly hogging power.

Seems to struggle between 60-80mph, sticks around 80. I have new monark nozzles, return lines, valves are adjusted, boost is set around 12psi, alda/banjo lines checked and double checked. Any thoughts? Thinking maybe tank strainer?

leathermang · #2 04-23-2011, 12:08 PM

As forced air enters the front of your car.... at some point it is possible that the turning of the fan , if bolted solid or clutch not working , will be working against the movement of air through the radiator... thus reducing cooling.
Old West type multiple slat windmills suffered from this..... as their rpms increased.... they appeared to the airstream more as ' solid objects'..... so air went around them instead of being caught for producing power. But in your engine compartment with a shroud around the back of the radiator and the fan in that place... once that occurs it can back up the air to outside the car and thus does no good cooling the engine.
The fluid coupling in the fan clutch allows higher pressure from the air movement to cause the fan to freewheel... thus not providing restriction to air flow at higher vehicle speeds..
It is also more efficient mpg wise and quieter to have it working correctly..
The FSM says the fan clutches should be stored ( like at the dealership ) vertically.... whether one could trust them to do that.. anyone's guess....LOL

ivandrocco · #3 04-23-2011, 02:14 PM

it's not freewheeling, it's always spinning. The clutch never seems to disengage. If I turn it manually, it turns the water pump pulley with it. I've already started another thread on this topic, however...

Stretch · #4 04-23-2011, 03:06 PM

Quote:

Originally Posted by ivandrocco

it's not freewheeling, it's always spinning. The clutch never seems to disengage. If I turn it manually, it turns the water pump pulley with it. I've already started another thread on this topic, however...

Can you turn the fan and water pump pulley with ease with the belt still on?

If so your belt could be slipping - which would account for a slightly warmer engine than normal.

I'm not trying to teach you to suck eggs but on the longest length of the V belt you should only be able to turn it by 90 degrees. Whilst you're there look out for muck / oil / worn belt.

If it is just the V belt that would be a cheap fix.

Otherwise when was the coolant last changed and does the cooling system leak...

...I'm sorry if this is too simple and you've already gone through all of this.

dagObx · #5 04-23-2011, 03:37 PM

If the car has the original radiator, it may be time for a change or flush-out. Also look to see if the air portion of the radiator is clogged with dead bugs, leave, etc.

I took the AC condenser off my car not long after I got it & was super surprised at the crap clogging up the radiator fins. A good power wash or car wash should remove most of the gunk. (BTW, I only raised the condensor up to get at the radiator; didn't remove all the AC lines from it.)

ivandrocco · #6 04-23-2011, 03:38 PM

Nope, takes some elbow grease to turn the fan with the pulley slipping under the belt. Haven't flushed the coolant, it's on the list. Tried to blast the bug lips etc from the radiator last week, seems clean enough.

leathermang · #7 04-23-2011, 04:54 PM

They make a ' comb ' for the radiator fins.....
you need to put a flashlight behind it to see if it is clear...
if you have 15 percent ( very common ) radiator fins bent or clogged by bugs...and 15 percent of the condensor... also very common... you can be those 15 percent do not line up perfectly... thus you can approach 30 percent blockage easily....and I was being conservative since many people never clean or check their fins....
That adds up to less engine cooling.....and less AC cooling...and pretty easy to fix...

Walrus · #8 04-24-2011, 01:58 PM

100+\- C does not sound like overheating to me... Assuming your cap is sealing well and correct pressure, it sounds about perfect.

ivandrocco · #9 04-24-2011, 03:10 PM

thought +/- 80c was perfect?

Walrus · #10 04-24-2011, 06:32 PM

what is the thermostat temp? I'm no expert, mind you. I prefer 90-100, but accept up to 105 without concern. Gasser may be different, of course.

80 is kinda cool, if you ask me... 176F. typical thermostat starts opening at stated temp, but is not fully open for approx 10 more degrees C, ie an 85C is fully open at around 94C...

layback40 · #11 04-24-2011, 09:04 PM

What is your timing chain stretch like?

Yak · #12 04-24-2011, 10:59 PM

What's the RPM @ 80? Is it getting to 4th or fighting in 3d? Does your kickdown work?

It could be a tranny problem hiding as temp/loss of power.

I thought the fan clutch was supposed to be a bit stiff at low RPM, then loosen up at faster rates. The FSM describes this as flowing the oil outwards for the first 1-3 minutes. Then the clutch disengages and the fan spins at engine speed, but not to exceed about 2100 RPM. Above 90-95 degrees the clutch re-engages. The test is to rev the engine to 4000-4500 until the temp gets to 90-95 and listen for the change in fan speed as the RPM goes from the disengaged ~2100 RPM to a higher ~3500 RPM.

This is paraphrased from the FSM.

ivandrocco · #13 04-24-2011, 11:58 PM

Kickdown works, shifts into 4th fine. My shifts feel solid and I think the points are more or less accurate. I think i'm around 4,000rpm at 80mph?

Haven't checked timing chain stretch. I'm at 210,000 miles so i'm assuming its a factor. Will triple check valves soon, and try to check stretch at that point. From what i've read, a mere visual check is impossible?

ivandrocco · #14 04-29-2011, 10:41 AM

did some general maintenance- replaced air and fuel filters, wastegate hose seemed inappropriate- too big and unclamped at the nipple on the front of the turbo. Replaced the hose and threw on a ziptie. Got some power back at high RPM, but i'm still lacking.

I had tried adjusting the rack damper before, but it didn't really do anything. Based on comments in another post, i removed it completely and reinserted it. By golly, solved my engine shake. Still unclear on proper adjustment- it doesn't noticeably effect anything during adjustment, I think re-seating did something. I got a 50-100rpm increase in idle. As I tighten it, the idle speed spikes for a second and then comes back down with each turn, but returns to basically the same speed whether I screw it all the way in or back it out.

Also, it's gold- does that mean it's been replaced?

Another peculiarity- my idle stop screw is plastered with some kind of gunk, looks like bondo. I started chiseling at it before coming to my senses and realizing that it someone must have plastered it for a reason. I'm guessing the whole seat broke off of the IP- If the screw was just un-threading itself for some reason they could have used thread lock. Think i'm gonna let this one lie for now, as rack damper did the trick.

I don't trust my linkage to be properly adjusted, i'm going to look there for further tuning.