Crushed top radiator hose when cold, 1987 - PeachParts Mercedes-Benz Forum

irhunter · #1 12-07-2006, 12:21 PM

Hi,

On my '87 300D, I notice the top radiator hose is "crushed" when the motor is cold. When I release the coolant cap, the hose goes back to normal. I have had other cars which had a steel coil inside the hose--which I assume has something to do with preventing this. This hose has no such coil.

Anyway, does someone know what is up?

Thanks,

Roy

pawoSD · #2 12-07-2006, 12:28 PM

That happens when a liquid (or air) in a sealed container drop in temperature....it causes contraction. Are you sure there is a 50/50 mix of MB coolant and distilled water in the system? I don't think it should do that normally....none of ours do.....

whunter · #3 12-07-2006, 12:40 PM

Quote:

Originally Posted by irhunter

Hi,

On my '87 300D, I notice the top radiator hose is "crushed" when the motor is cold. When I release the coolant cap, the hose goes back to normal. I have had other cars which had a steel coil inside the hose--which I assume has something to do with preventing this. This hose has no such coil.

Anyway, does someone know what is up?

Thanks,

Roy

You have a bad radiator cap.

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 300D Turbo
Part: Expansion Tank Cap
Note: 1.4 Bar
G1040-30351 Expansion Tank Cap Germany IN STOCK $7.51
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1YE1FF2PQ1YN0R2ATD&year=1987&make=MB&model=300-DT-002&category=G&part=Expansion+Tank+Cap

Replace it, and all will be well.

Merry Christmas.

rrgrassi · #4 12-07-2006, 12:41 PM

Roy,

Actually, on older cars, the metal spring was in the lower radiator hose to keep the hose from collapsing while the engine was running.

With the upper hose collapsing when cold is a demonstration of thermo dynamics and the pressure inside the cooling system being less than atmospheric pressure.

This can happen if coolant level is low, as air is now in the system. Cold air contracts, warm air expands.

Opening the coolant fill cap will draw in air and equalize the pressure. It also means that your system is not venting properly, or you are low on coolant.

whunter · #5 12-07-2006, 01:15 PM

Quote:

Originally Posted by rrgrassi

Roy,

Actually, on older cars, the metal spring was in the lower radiator hose to keep the hose from collapsing while the engine was running.

With the upper hose collapsing when cold is a demonstration of thermo dynamics and the pressure inside the cooling system being less than atmospheric pressure.

This can happen if coolant level is low, as air is now in the system. Cold air contracts, warm air expands.

Opening the coolant fill cap will draw in air and equalize the pressure. It also means that your system is not venting properly, or you are low on coolant.

A bad radiator cap prevents system cold equalization, generally called cold venting, and I see it often.
A cap is cheap, mine is replaced every year.

Your other points are also accurate.

Brian Carlton · #6 12-07-2006, 01:27 PM

Quote:

Originally Posted by whunter

A bad radiator cap prevents system cold equalization, generally called cold venting, and I see it often.
A cap is cheap, mine is replaced every year.

Is that cap designed to prevent accumulated vacuum in the system.....and, if so.......to what level?

Most systems have an absolute pressure below atmospheric when cold.......after running.......as evidenced by the inrush of air when opened. All of these caps cannot be NG.........???

whunter · #7 12-07-2006, 02:13 PM

Quote:

Originally Posted by Brian Carlton

Is that cap designed to prevent accumulated vacuum in the system.....and, if so.......to what level?

Most systems have an absolute pressure below atmospheric when cold.......after running.......as evidenced by the inrush of air when opened. All of these caps cannot be NG.........???

However, it is the cheapest ($7.50 USD) starting point for any cooling system diagnosis.

This is another reason why I replace the cap on my car every year, it gives me a known good cap for diagnosis.

This year the average for MB I worked on has been seven out of ten caps where bad.

I would rather replace three good caps, than miss one bad cap.

The cap, thermostat, belt and hoses are the cheapest units on your car, that can potentially wreck the engine.

What is your engine worth to you?
Would you knowingly choose to ignore/refuse service on these critical items?
My sincere hope is that no forum member would risk their engine over these cheap items.
The sad fact is that I see many MB that need all of these items at once, due to the previous owners LACK of maintenance.

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 300D Turbo
Part: Thermostat Kit
Note: 80 degree
G4001-49781 Thermostat Kit Wahler IN STOCK $24.50
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1YE1FF2PQ1YN0TDGMP&year=1987&make=MB&model=300-DT-002&category=All&part=Thermostat+Kit

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 300D Turbo
Part: Radiator Hose
Note: Lower
G2000-16382 Radiator Hose Germany IN STOCK $72.16
http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1YE1FF2PQ1YN0TDGMP&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1987&product=G2000-16382&application=000017660

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 300D Turbo
Part: Radiator Hose
Note: Upper to thermostat
G2000-16376 Radiator Hose APA IN STOCK $11.81
http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1YE1FF2PQ1YN0TDGMP&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1987&product=G2000-16376&application=000040490

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 300D Turbo
Part: Radiator Hose
Note: Lower
G2000-16380 Radiator Hose Lemforder IN STOCK $6.08
http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1YE1FF2PQ1YN0TDGMP&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1987&product=G2000-16380&application=000040496

Vehicle: 1987 Mercedes Benz 300D Turbo
Part: Heater Hose
Select one of the products from below
-----------------------------------------
Heater Hose
12 X 19 mm : 1 meter
-----------------------------------------
Heater Hose
15 X 22 mm: 1 meter
-----------------------------------------
Heater Hose
18 X 25 mm : 1 meter
-----------------------------------------
Heater Hose
Valve to Auxiliary Pump Chassis: -A 289309
------------------------------------------
Heater Hose
Engine to heat exchanger Chassis: -A 289309
------------------------------------------------
Heater Hose
Recirculating pump to
return line Chassis: -A 289309
----------------------------------------------------
Heater Hose
Return line to engine
Chassis: -A 289309

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1YE1FF2PQ1YN0TDGMP&year=1987&make=MB&model=300-DT-002&category=All&part=Heater+Hose

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 300D Turbo
Part: Multi Rib Belt
Note: 21.36 X 2145
W1000-21016 Multi Rib Belt Conti IN STOCK $27.03

W1000-21016 Multi Rib Belt Bando IN STOCK $20.92
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1YE1FF2PQ1YN0TDGMP&year=1987&make=MB&model=300-DT-002&category=All&part=Multi+Rib+Belt

Acc. Belt Idler Pulley
Acc. Belt Tension Adjuster
Acc. Belt Tension Damper
Acc. Belt Tension Spring

irhunter · #8 12-09-2006, 08:48 AM

I was hoping no one would say I had head problems.

retmil46 · #9 12-09-2006, 12:07 PM

About a month ago, test drove an '87 at a dealer, checking it out for a friend in another state. Still had the factory cap on the expansion tank, after 20 years and 136K miles.

Doing the check for oil in the cooling system (for a cracked head), I removed the radiator cap......

Then I removed the spring, and then the rubber diaphragm!

It was so old it had literally fallen to pieces, the cap holding everything in place once screwed on.

That, the red mung growing in the expansion tank, and a few other items that screamed "no maintenance", lead me to tell my friend to avoid that beast.

I did do the dealer, and any unknowing buyer, a small favor. I told him what I'd found, and that if he wanted to have a prayer of ever selling that car he'd best flush the cooling system and install a new cap.