Knock, Knock. Who is there? Bad motor. Knock, Knock, Knock, Knock... - PeachParts Mercedes-Benz Forum

VintageBenz.org · #1 05-22-2009, 12:52 AM

Well I have not updated VintageBenz.org but our wedding is in 4 days and we just drove the car back from Grand Rapids after installing the new air suspension. We hoped to take it to the paint shop this weekend for a quick scuff and buff before the reception (info at http://awesomewedding.info).

Well one the way home it did not feel like it was going into overdrive and I made a stop only a few exits into the trip. As I slowed down I heard what I did not want to hear....... knock.

The oil level had decreased slightly in the short time from when I checked it before we left. Sure enough it was leaking around the drain plug so I added some to correct this problem. I also know that the Zenith's need to be adjusted asap and I am going to stop and see Frank to get his thoughts on the matter.

That is why I am here. Any suggestions from the experienced Mercedes community? If it was in fact running lean yet the temperature did not rise about normal could any damage have occurred? What is the best way to test/correct this, keep in mind that I have been a fuel injection guy my entire life and this is only my second carburated vehicle. I am afraid to make any adjustments after ruining the Briggs and Straton on my lawn mower last year.

The main problem is time constraints. We hoped to have it a little closer to completion so that it could be parked on the island for our reception on May 30th. ** Also all everyone here is more than welcome to attend and if you have a car worthy of displaying on the island please let me know asap so we can arrange it **

Any help / thoughts are much appreciated!

Take care,
Bryan Plaunt

jwhughes3 · #2 05-22-2009, 06:22 AM

I wish I had constructive comments on your knocking but I can only offer that if the oil level was still on the dipstick at all then damage is unlikely. If it was dry, then I would pull the pan again and inspect the mains before running it again.

I looked over your documentation of the restoration - very nice pics and detailed descriptions. I especially like the pic of the rat.

I hope you are able to get it going again soon after the honeymoon and enjoy it for many years to come. Makes me want to get one too

Best wishes for your wedding day.

John in San Antonio

t walgamuth · #3 05-22-2009, 06:34 AM

If the oil was not dry, beign a little low should not have damaged the motor unless it was so so low the pump was starving for oil.

On the other hand if its very low it might carry pressure standing still but starve on a curve or stop where the oil flows away from the pump and make a knocking sound. This temporary knock might not do damage if corrected immediately.

As for running lean, if it were it would show up in poor running I would think like budking or stumbling. I think running a bit lean would not be a problem from one trip as far as damaging your pistons.

Good luck!

JimFreeh · #4 05-22-2009, 07:20 AM

Quote:

Originally Posted by jwhughes3

I hope you are able to get it going again soon after the honeymoon and enjoy it for many years to come. Makes me want to get one too

Best wishes for your wedding day.

John in San Antonio

What, a wife or a car?

Jim

VintageBenz.org · #5 05-23-2009, 11:44 AM

Good one Jim

Thanks for the reassurance guys. I am headed to the hanger we are storing it at this morning to do another assessment before preparing to repair the worst. I have the Star Classics discs but man are they lacking! There is information regarding both diesel and fuel injection in the 230S section. I just wanted to see how to access the mains and couldn't find even a point in the right direction anywhere. Oh well hopefully I won't even need to do that. I will post an update after returning from the airport, hopefully it will be some good news! I also have to change the oil on the W210, attach the air cleaner to the W126, and get my show car cleaned off and prepared for my wedding!! Does anyone have a flux capacitor I borrow?

Thanks for the help guys and wish me luck!

- Bryan Plaunt

VintageBenz.org · #6 05-23-2009, 01:31 PM

I have found this thread M180 Oil Pressure very helpful and going to check the oil pressure relief valve and see if she makes noises when cold *crossing fingers*

VintageBenz.org · #7 05-23-2009, 06:39 PM

Well the oil pressure shoots right up to the top the second you start it. Unfortunately there is still a knock...

I looked for the oil pressure relief valve but only found a bolt for a timing gear under a plate with four bolts on the front of the block. There is also a very large bolt near there, it is larger than my 21mm wrench, and I didn't know if it could be under there. My future wife asked if the pressure gauge could be off only reading full bore. The force is strong with her

I loosen the 14mm'ish bolt from the line going through the firewall into the side of the block only to find that it is securely fastened, I only assume this could be the oil pressure sending unit.

She also noticed that the fan was wobbling like crazy and making it hard to diagnose exactly where the knock was coming from. We began to take the bolts off only to realize the it must be attached to the water pump since coolant came flying out. We came home and checked the 68 fan and there is no play at all.

We had to go get a few more parts for the suspension and I am going to try and grab a wrench to get those large bolts loosened.

Anything you guys suggest we try next?

jwhughes3 · #8 05-24-2009, 03:51 AM

I would think it wouldn't help tp have the loose fan knocking around - usually when I have a sound like that I use a wooden dowel pressed to my ear at various points to pinpoint the source. Knowing where it comes from helps determine where to look next.

Luck!

John in San Antonio

(Jim I mean the car - already have the wife and she won't let me have 2 of those!)

wbain5280 · #9 05-24-2009, 01:42 PM

Air suspension and zenith's are mutually exclusive.

What model do you have and please post some pics.

VintageBenz.org · #10 05-25-2009, 01:35 AM

Well I started her up today when we stopped over to do some more work and she didn't sound as bad. Nothing has really changed other than loosening the fan until we can replace it with the one from our 68. Cross your fingers and hope for the best.

The air suspension is not OEM. I work for the Air Lift Company and used our air springs which are meant to replace the coil springs and allow for both height and spring rate adjustment. I have ridden in many vehicles with air suspension and between our new Dominator bags and the Bilstein's I got from Phil I am very impressed. So now I can also have the car rest on the ground or drive it at various heights and spring rates. I will post some video after I have finished installing the air management system tomorrow. I went with a 5 gallon tank, dual Viair 480C compressors, and paddle valves which will be replaced with our digital control system if I get switch happy again

There is nothing like pulling into a parking spot and laying her out with a nice *Whoooooshhhh*.

Wish me luck tomorrow guys. I need to spend an hour or two updating the site. With the wedding 2 days away it is hard to find time though!!

t walgamuth · #11 05-25-2009, 10:23 AM

I guess I'd get the fan sorted. It could be the source of your "knock". Bad water pump bearings?

zenuff · #12 05-27-2009, 05:53 PM

Keep an eye on the oil pressure gauge is my advise, and listen for expensive noises.
My old lady finally died last week when the oil pump failed.
I had some bearing wear and that would cause a low pressure and clacking sound after warm. It was totally quiet when cold with full pressure.

And then I was driving along minding my own business and i heard a bad sound looked at the oil pressure it was at zero!
As soon as I let off the gas to pull over it went boom and the rod went flying out the side of the case. ( I went back and picked it up off the side of the road.)

I hope its nothing but a loose fan noise or something simple. P.S. I really enjoy your website.

Good luck

jwhughes3 · #13 05-29-2009, 12:04 AM

Congrats now!

John in San Antonio

t walgamuth · #14 05-29-2009, 06:00 AM

Quote:

Originally Posted by zenuff

Keep an eye on the oil pressure gauge is my advise, and listen for expensive noises.
My old lady finally died last week when the oil pump failed.
I had some bearing wear and that would cause a low pressure and clacking sound after warm. It was totally quiet when cold with full pressure.

And then I was driving along minding my own business and i heard a bad sound looked at the oil pressure it was at zero!
As soon as I let off the gas to pull over it went boom and the rod went flying out the side of the case. ( I went back and picked it up off the side of the road.)

I hope its nothing but a loose fan noise or something simple. P.S. I really enjoy your website.

Good luck

Yipes!

If my car had a noise from loose bearings I would not drive it around the block.

Lack of oil pressure is the kiss of death to an engine.

zenuff · #15 05-30-2009, 03:06 PM

Quote:

Originally Posted by t walgamuth

Yipes!

If my car had a noise from loose bearings I would not drive it around the block.

Lack of oil pressure is the kiss of death to an engine.

Very true.. Unfortunately it was my only car at the time. i am building another car right now and hoped I could get by until it was finished, but the engine didnt hold that long.

But on the bright side the engine still runs on 5 cylinders and doesnt have a bit of knock! It vibrates a little though.