Welcome Guest. ( logon | register )   
FAQ Member List Albums Today's Posts Search

PointedThree :  Vans, Trucks, SUVs and Other Forums : G-Class : Overheating? Confused!

Page 1 of 2 12
Overheating? Confused!
Topic Tools Message Format
Author
Posted 12/6/2008 9:49 AM
kashi123
Veteran




Date registered: Apr 2006
Location: UK, Netherlands
Vehicle(s): Mercedes 300GD OM606A Pickup; Mercedes 300GD
Posts: 150
100
Overheating? Confused!

Hi all,

I hope you can give me some advice on the following because it is driving me insane.

I have a 300GD which according to the in dash gauge is close to overheating, it will hover just below the red mark but never actually go into it. This will be uphill or at idle.

The backgound is that I have put in a new radiator and thermostat when I got it because the radiator was just held together with rust, no idea if it overheated before I bought it.

I have hooked up an aftermarket gauge to the original sender which reads between 110 and 120 Degrees C where the original gauge hovers round the red mark.
Interestingly the temperature in the header tank is 82 degrees C
The top radiator hose and the headertank get hot, however the rest of the rad below that is cold including the bottom hose.
When I peer into the radiator with the cap off I can see (brown) water moving slowly from right to left, facing the vehicle.

I have swopped the senderunit with a spare that I had and it still reads hot!

Funny thing is that the engine doesn't 'feel' hot to the touch, at least compared to my other G with a 617a which is like an oven under the hood but only registers 1/4 on the gauge.

I thought it might be an airlock and read somewhere to fill the thermostathousing with coolant through the top house , so I have done that as well.

On a side-note: the oilcooler is stone cold as well.

The engine runs sweet as a nut but before I got it has been stood idle for a number of years.

Now I have run out of options and any and all advice would be gratefully recieved


Don't you just love G-wagens! I still haven't got round to changing the oil in the 617a to see if that will bring the oilpressure up a bit. Need more time and less work

Thanks

Richard



(RedG 005.jpg)



Attachments
----------------
Attachments RedG 005.jpg (137KB - 1 downloads)
#137430
Top of the page Bottom of the page
Author
Posted 12/6/2008 10:12 AM
hipine



Date registered: Jul 2006
Location: US, CO, Bailey
Vehicle(s): 460 1980 280GE w. 617A
5000
RE: Overheating? Confused!

Hi Richard,

Kudos to you for verifying correct things first - that the engine temperature actually is high, not just a bad gauge reading. And it IS high. It shouldn't get over 90C in any case. My 617A runs at 165F on the thermostat and about 185F on the fan clutch. I'm not saying these are "right", just the way that works well for me. I don't want to hijack the thread to what the temp "should" be, just to note that you did a good job in verification and that your factory temp gauge is probably a good indicator and should be back below center or lower when all is well.

The first thing Id' do in a case like this is try running it with the thermostat completely removed, just as a diagnostic tool. If it still runs hot then you know it isn't an issue with the thermostat or the coolant fill. If it cools off when the t-stat's out, maybe the t-stat was broken, incorrect, or improperly installed. I'm not sure if the 300GD thermostat has a recirculation blocker (if it did, the test above wouldn't work right), but I don't think so from the one I've seen. The test above should work fine.

Next is I don't like the sound of your brown coolant. There could be a rust blockage in the head causing coolant to flow slowly there and cause it to run hot. If the t-stat test above shows it still running hot with the t-stat out, I'd have the system flushed until it shows nothing but translucent (color of your choice ) coolant flowing in there. The coolant flush is a good idea in any case of course, but not necessarily root cause of your overheating. Make sure you also remove the small threaded plug from the right side of the block when doing this flush. Rust can collect down there. Your nice new radiator may also be plugged with rust washing out of the engine. Flush the radiator out well too and make sure that when both hoses are removed, directing water in the top hose port results in clean clear water flowing at full speed out the lower hose pipe.

If you get the system flushed out, and the coolant is clear and it's still running hot with the t-stat out, then I'd go looking to verify the flow through the radiator and that the water pump is moving enough water. But I would definitely do the two things above before moving into trickier and more expensive verifications.

All the best, and let us know haw you make out.

-Dave G.




Edited by hipine 12/6/2008 10:18 AM
#137434 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/6/2008 1:37 PM
Inkblotz
Expert




Date registered: Apr 2006
Location: Georgia
Vehicle(s): 90 300GD "Thundering Turtle II", w/ 603A turbo
Posts: 2808
2000
Re: Overheating? Confused!

I agree with Dave G on flushing and removing the thermostat for a test run.

Adding to all that I have a few questions/suggestions. Is the thermostat a factory authorized unit (such as a Behr unit) there are many cheap faulty aftermarket thermostats out there. This is one place where you don't do aftermarket.

Also regarding the thermostat there have been problems where people have installed them backwards and cases where air gets trapped in that chamber and thus never circulates coolant (IE your cold lower radiator hose). Either one of these will cause what you are experiencing.

Check to make sure it is in the right way. Also some folks have drilled 2 small holes into the top lip of the thermostat round metal disk (not the housing but the disk itself) which is just enough for the air to escape. It seems to work for those who cannot get the air out.

I also agree with Dave on the brown fluid with one exception make sure it is rust and not oil. It is odd that the oil cooler remains cool. That tells me something is plugged. You may want to remove it, take it to a radiator shop and have them clean it out for you. Might need to do the radiator again as well if rust particles have found their way into the radiator.

All are very straight forward checks and repairs.

My 2 cents worth.
Mark

Edited by Inkblotz 12/6/2008 1:41 PM
#137446 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/6/2008 2:34 PM
louwdj
Veteran


Date registered: Feb 2007
Location: Johannesburg South Africa
Vehicle(s): 89 W460 230GE 5 door; 82 W123 230e; 99 W210 E240
Posts: 126
100
Re: Overheating? Confused!

I support what has been said so far. In addition, make sure that you have the right mix of anti-freeze.
#137449 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/6/2008 3:23 PM
kashi123
Veteran




Date registered: Apr 2006
Location: UK, Netherlands
Vehicle(s): Mercedes 300GD OM606A Pickup; Mercedes 300GD
Posts: 150
100
Re: Overheating? Confused!

Thank you Gentlemen,

I will remove the thermostat tomorrow, yes it is a cheap aftermarket one. The thermostat that was in there had a big hole drilled in it??
I might just get an orginal Mercedes one just to be sure

The water doesn't look oily just very brown. If taking the thermostat out doesn't help I will flush the radiator and engine (not looking forward to that!)

Dave, I even took the old temperature sender, hooked it up to the aftermarket gauge and then rigged up a pan of boiling water, a battery and said gauge to verify the reading on the gauge was correct. Sad or what!

Will keep you informed,

thanks again

Richard
#137450 - in reply to #137449
Top of the page Bottom of the page
Author
Posted 12/6/2008 3:58 PM
Loki Laufeyjarson



Date registered: Apr 2006
Location: 66°N, 19°W
Vehicle(s): 300GD 1983.
500
Re: Overheating? Confused!

Inkblotz - 12/6/2008 5:37 PM I agree with Dave G on flushing and removing the thermostat for a test run.
Adding to all that I have a few questions/suggestions. Is the thermostat a factory authorized unit (such as a Behr unit) there are many cheap faulty aftermarket thermostats out there. This is one place where you don't do aftermarket.
Mark


In the beginning I had heat problems on my 617 with aftermarket thermostat. Tried two or three before I got my hands on original BEHR from the MB dealer.
I therefor jump into the line of suggesting removeng the thermostat, If that lowers temperature - go for BEHR...

Loki -heatet like allways
#137453 - in reply to #137446
Top of the page Bottom of the page
Author
Posted 12/6/2008 4:34 PM
hus55
Expert




Date registered: Apr 2006
Location: north cyprus,lapta.
Vehicle(s): 300GDS, G300 LONG,300GDT CLK55 AMG CAB.
Posts: 2228
2000
RE: Overheating? Confused!

good topic richard

i have the same problem with my cab. i will also check the t-stat as my rad was flushed and cleaned by a rad specialist last summer. i wouldnt be suprised if the t-stat is 18 years old or a non oe one

but the water pump is also an aspect worth checking.

i remeber Isa [mortinson] talking of this subject with an interesting cure too egarding the pulley size on the pump and t-stat model being changed to a hotter climate one.
#137455 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/6/2008 6:04 PM
NOPEC
Extreme Veteran




Date registered: Feb 2008
Location: Babylon, Long Island, NY
Vehicle(s): 1985 Mercedes 300GD
Posts: 346
300
Re: Overheating? Confused!

The hole in the radiator is a modification promoted on dieselgiant.com
#137458 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/7/2008 1:36 PM
hipine



Date registered: Jul 2006
Location: US, CO, Bailey
Vehicle(s): 460 1980 280GE w. 617A
5000
Re: Overheating? Confused!

I hope the thermostat is the culprit. That's an easy fix. But even if it is, you should get the system flushed out, probably by a good professional. The rusty brown water is a bad sign for the engine. I don't flush those systems myself any more. Too big a mess and too much crap spilled on the ground. I take it to someone I trust and spend the $200 for THEM to go through the roughly 4 hour procedure it takes to do it right. Money well spent in my opinion.

Some thermostats have the little hole drilled in them right out of the box, some don't. It should only be a very tiny hole, around 1mm, and the thermostat should be oriented so the hole is at the highest point.

Good luck my friend.

-Dave G.
#137513 - in reply to #137450
Top of the page Bottom of the page
Author
Posted 12/7/2008 2:06 PM
kashi123
Veteran




Date registered: Apr 2006
Location: UK, Netherlands
Vehicle(s): Mercedes 300GD OM606A Pickup; Mercedes 300GD
Posts: 150
100
Re: Overheating? Confused!

Cheers guys, didn't get round to it today so now it will have to wait until next week.
What I have noticed is that the higher the revs the cooler (relatively) she runs.
As soon as I change down a gear and really give it some the temperature drops a bit, the same at idle if it is hovering round the red and I gun the engine ou can see the needle slowly moving back down.

I will take you advice though Dave and have the rad and engine flushed. I found an old Behr thermostat lying in my other G so decided to check if that was ok with the boiling pan of water method, it was knackered. That is probably why it was there....

Why is the brown water a bad sign for the engine? Even after it has been flushed ?(said in a tone of trepedation, bearing in mind your signature......)

Thanks, as always for all your advice

regards

Richard
#137516 - in reply to #137513
Top of the page Bottom of the page
Author
Posted 12/9/2008 3:44 PM
hipine



Date registered: Jul 2006
Location: US, CO, Bailey
Vehicle(s): 460 1980 280GE w. 617A
5000
Re: Overheating? Confused!

kashi123 - 12/7/2008 12:06 PM

...Why is the brown water a bad sign for the engine? Even after it has been flushed ?(said in a tone of trepedation, bearing in mind your signature......)

....


Only becuase it means there's enough internal rust to be releasing particulates into the water. Whatever's shedding the particles needs to be flushed out so the coolant can do it's job of neutralizing whatever rust remains on the internal surfaces of the block and head.

Your comments about the effect of revving bring a couple things to mind

1- an internal partial blockage will allow more flow as more "pressure" is put on the remaining open passage by the faster spinning water pump

2- the corrosion evident in your system indicates there's a possibility that the water pump vanes or housing may corroded to the point that the pump is not as efficient as it should be and not pumping properly.

In light of this new info on effects of revving, after verifying the thermostat and flushing the system, I'd move on to verifying the condition of the water pump and housing.

Good luck!

-Dave G.

Edited by hipine 12/9/2008 3:45 PM
#137720 - in reply to #137516
Top of the page Bottom of the page
Author
Posted 12/13/2008 11:11 AM
kashi123
Veteran




Date registered: Apr 2006
Location: UK, Netherlands
Vehicle(s): Mercedes 300GD OM606A Pickup; Mercedes 300GD
Posts: 150
100
Re: Overheating? Confused!

Quick update:

Today in the pouring rain I changed the thermostat for an original Mercedes one, just to be sure. Made no difference whatsoever so threw my toys out of the pram and put it back in the shed where it lives. I will be away now for three weeks so it looks like tackling the waterpump next, joy!

To add insult to injury my other G failed its annual road worthiness test (MOT) yesterday on an assortment of electrical gremlins, it was FINE when I took it in!

Not having a G-ood day, bit fed up with them now.

Thanks to all who suggested cures for it.
Am going to calm down, get Christmas out of the way and then try again!

Cheers

Richard
#138105 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/13/2008 12:24 PM
dai
Expert




Date registered: Apr 2006
Location: Oregon USA
Vehicle(s): 300GD 300TD BMW R100RS Landini 80F
Posts: 2110
2000
Re: Overheating? Confused!

I just had a bizzare problem that related to cooling. The alternator had eaten through the bottom mount due to vibration. That made the belt slip but in a non obvious way. So it wasn't charging correctly and the pump wasn't spinning at the right speed. No slipping noise. Have you investigated belt tension? Does it seem real firm or does it have some extra play. Can you shift the alternator with your hands or is it rock solid?
I will make a thread about my strange alternator issue and fix.

-Dai
#138106 - in reply to #138105
Top of the page Bottom of the page
Author
Posted 12/13/2008 1:01 PM
hipine



Date registered: Jul 2006
Location: US, CO, Bailey
Vehicle(s): 460 1980 280GE w. 617A
5000
Re: Overheating? Confused!

dai - 12/13/2008 10:24 AM

I just had a bizzare problem that related to cooling....


Wow. Under the heading of, "Just when you think you've seen it all...."

Well, Richard, I wish you luck when your motivation returns. In the mean time, Happy Holidays.

-Dave G.
#138107 - in reply to #138106
Top of the page Bottom of the page
Author
Posted 12/13/2008 1:04 PM
kashi123
Veteran




Date registered: Apr 2006
Location: UK, Netherlands
Vehicle(s): Mercedes 300GD OM606A Pickup; Mercedes 300GD
Posts: 150
100
Re: Overheating? Confused!

Thanks Dai,

That is a good tip, will investigate tomorrow if weather permitting, also just realised I fitted the thermostat without looking at the orientation of the arrow, so out it comes again.

Oh well, at least I am creating a bond with it now.......

Also realised I have a spare waterpump on my blown spare 617a engine so no excuse really to try that one..... Unless they are different?

cheers

Richard

Edit: sorry Dave, our posts must have crossed in cyberspace, motivation is slowly returning already
A Merry Christmas to you and yours!

Edited by kashi123 12/13/2008 1:06 PM
#138109 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/13/2008 1:17 PM
hipine



Date registered: Jul 2006
Location: US, CO, Bailey
Vehicle(s): 460 1980 280GE w. 617A
5000
Re: Overheating? Confused!

kashi123 - 12/13/2008 11:04 AM

Also realised I have a spare waterpump on my blown spare 617a engine so no excuse really to try that one..... Unless they are different?


I'm pretty sure they are different, Richard. But Dai probably has the best experience along these lines. I'd be getting the block and head flushed out first though to get rid of the rusty water.

All the best to you as well. As for me, and strange happenings, I'm on my way to the doc this morning because while out Christmas Carolling with Wyatt and the Cub Scouts last night, something blew into my eye that is aparently still lodged in there. What a PITA. Gotta get it squared away this morning though because I have to change oil in the G this afternoon before the next cold front rolls through. Tomorrow's high is supposed to be about 10F here.

-Dave G.
#138110 - in reply to #138109
Top of the page Bottom of the page
Author
Posted 12/13/2008 2:54 PM
dai
Expert




Date registered: Apr 2006
Location: Oregon USA
Vehicle(s): 300GD 300TD BMW R100RS Landini 80F
Posts: 2110
2000
Re: Overheating? Confused!

If you are having the problem with a stock G diesel motor, it has a very different and very expensive water pump compared to the 617A. The stock G pump uses a single belt pulley and it has a broad cast flange that is quite different than the turbodiesel motor. The only reason I can think of that the pump might be a problem is that the impeller has been eaten away with corrosion. I had this problem with a large Peterbuilt truck I bought used. I think it had frozen and parts of it broke off when it was turned. But in that case the cooling was worse at higher RPMs because it would not circulate coolant correctly.

-Dai
#138116 - in reply to #138110
Top of the page Bottom of the page
Author
Posted 12/13/2008 3:40 PM
Ed Mclass
Expert




Date registered: Apr 2006
Location: Nashville, Tennessee
Vehicle(s): 1958 180a, 2010 GLK, 2000 G 500, 2005 SLK 350
Posts: 1205
1000
Re: Overheating? Confused!

Was mention made of the proper radiator cap and fitment? A leaking cap will also cause these symptons but you should smell or see a coolant leak too.
#138118 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/14/2008 5:28 AM
mennolijk
Member




Date registered: May 2007
Location: the Netherlands,Harderwijk
Vehicle(s): Puch 300GD-1989,Vito 115-2006
Posts: 47
25
Re: Overheating? Confused!

I had a cooling problem with my G,same symptoms you describe.In my case the viscious clutch of the radiatorfan was worn out.
Menno
#138181 - in reply to #137430
Top of the page Bottom of the page
Author
Posted 12/14/2008 9:47 AM
kashi123
Veteran




Date registered: Apr 2006
Location: UK, Netherlands
Vehicle(s): Mercedes 300GD OM606A Pickup; Mercedes 300GD
Posts: 150
100
Re: Overheating? Confused!

Thanks, all good tips,
Changed the radcap with the one off my other G, no difference.
I will see if I can 'lock' my viscous fan, hopefully that is it/
But first I will flush the engine and rad because that needs to be done.

Thanks again

Richard
#138192 - in reply to #137430
Top of the page Bottom of the page
« View previous thread :: View next thread »
Page 1 of 2 12
Forum Jump :
All times are EST.  The time is now 9:51:33 AM.

Execution: 0.390 seconds, 110 cached, 10 executed.