My cold blooded 240..part 2
 

I posted earlier about my 81 240d running cold even in the summer. Now it barley makes it up to 60* after a long haul.
I put in a new mb T-stat and run a 50/50 mixture of coolant. I have checked the engine temps/ head temps with my infared heat gun and she does run cool..around 150* at best. My gauge appears to be fine.
btw.. I did put in a new bosch water pump a few weeks ago.. had a small drip from teh weep hole...................so my question is....

should I run cardboard in front of the radiator ?.........or
should I remove the fan and and fan shroud until spring ( and watch teh gauge) when temps get above 65* ambient?

EDITED: ALL THREE THREADS ARE NOW COMBINED INTO THIS THREAD

Could the viscous fan clutch be stuck? To much airflow will make over efficient cooling.

240s have a rigid
 

fan.

yes you may need some cardboard in cold weather. be careful with it though. on the highway you may overheat. start with a small piece.

tom w

I personally wouldn't panic about it running that temp. Give it a good italian tune up occasionally :) I would also see if you can get an after market thermo that runs a little hotter if you are really concerned.

Are you sure the stat is working and installed correctly (not backwards)? Can you feel hot coolant circulating to the radiator when the temp is less than 80C? If so, I would recheck the stat. You shouldn't need to block the radiator to run at the correct temp.

I dunno about a 240D, but my FSM states the minimum operating range for my 220D is 70*c, not 60*c.
Not getting up to full operating temp is not a good thing. You need the heat to get any condensation out of the oil, and for all the running tolerances to get to proper spec. The engine will wear faster and make less power when cold.
I definately would NOT do an italian tuneup unless the engine had been up to full operating temp for some time.

If you go to www.********.com, they have thermostats listed for your vehicle up to 195*F.
If it is interchangable, they also list Behr brand 87*c thermostat kits ('stat and o-ring) for my 220D.

Since you have one of those nifty temp guns (I'm jealous) you could use it to check when the thermostat opens. If you read hot coolant starting to enter the radiator hose when the engine is still pretty cold then you probably have a bad thermostat.

No clutch fan on my 240... direct drive

btt...

I put some cardboard in front of the radiator and drove 20 miles....

no change....whats up with that?

are you sure the temp
 

guage is working?

did you say your heater produces heat?

tom w

Yes gauge is right on according to the infared thermometer pointed on the head.... and yes I get lukewarm heat...not hot

i would suspect
 

the stat. i would prob remove it and check to be sure it is installed correctly and use a pan with boiling water to check its function. when installed, the flat disc goes down. easy to get wrong i have done it.

tom w

DID you happen to point
 

the IR thermo @ the oil cooler??

Perhaps the thermostat for the oil cooler is stuck open. Thats about the only thing that might explain it your issues. Its supposed to open @ about 95 on my 300d.

An improperly installed coolant thermostat wouln't really cause your issues.

Never knew there was a t- stat for the oil cooler... where is it located?.. on the cooler I assume ?

http://rbk3.com/mbz/tsm/MBZ18-120%20OIL%20THERMO.pdf

http://rbk3.com/mbz/tsm/MBZ18-005%20OIL%20SYS.pdf

It did on my 300D. Temp stayed at 60C or less, stat was installed backwards by PO. The stat may have also been failed, replaced it and car ran at 80C, even in very cold temps.

That does not make sense to me, looking at the diagram on pg 3

http://rbk3.com/mbz/tsm/MBZ20-005%20Coolant%20circuit.pdf

a t-stat installed backwards should keep all hot water circulating within the engine block... unless the pressure from the pump is enought to defeat the spring of the thermostat.

Either way, this site rocks, I keep learning new things every time I drop in here (almost every day).

I don't know how/why my backward stat caused the engine to run cool. Maybe there is enough pressure to force it open, or maybe it was stuck open in addition to being backwards. The first time I drove mine in cold weather I noticed it was never getting over 60C, so I brought it to my Indy to replace the stat. He replaced it and told me it had been backwards. He didn't test the old one. With the correct installation, I have driven at highway speeds at -5F and the temp stays at 80C with plenty of cabin heat.

240D too Cool..check my theory?
 

My 81 240D is too cool .... I have done everything but pull the fan and shroud ( that's next). I cannot get this car up to temp no matter what.
I put a block heater in last night and it makes the startup easy and a faint bit of warmth can be felt very soon after takeoff. Glo plugs seem to be OK as I asked in another post.
Even in the summer I had difficulty hitting full 80*c on a hot day.
What I have done...
New bosch water pump ( weep hole was leaking)
Bosch 80* thermostat and in correctly
I have cardboard and taped off the entire front of the radiator and this made very little change.
Head temps with Infared thermomoter reads 130 at best in these cold temps ( 20*) I am at 4500' elevation and low 20s at night and 30s in daytime.
no restrictions in the vents etc.. fan blows awsome.
Dash Temp gauge reads 50*c and goes no higher even with cardboard.
Should I pull the fan and shroud?.... will this really help?

Something is not right, my 240D was running at 80C today within 5 minutes (with about 20-25F outside temperature). When the engine is as warm as it gets, can you feel hot/warm coolant going to the radiator? The radiator and the upper hose should stay cold until the thermostat opens at 80C. If you are getting flow to the radiator at less than 80C it pretty much has to be a problem with the thermostat opening too soon. If the thermostat is working correctly, blocking the radiator, removing the fan, etc. should no make any difference anyway. I would be tempted to replace the thermostat again (with an 80C OEM) just to make sure. I just can't think of anything else that would cause this. Anyone?

have the cooling system and rad. cap pressure tested. if the system cant pressurize it wont heat up right

Are the German motorad thermostats the "fail open" type?

when doing the block heater last night I took the thermostat out and it looked fine in the closed position. I figured if it failed it would fail open causing teh motor to run too cool....

Is there a possibility that your temerature gauge or sender is out of calabration? Do you have a warm heater? Can you get your hands on a infared temerature probe for a few minutes to check block temp when warm? Probably above does not apply as you mention little cabin heat. To find out if constant circulation is a problem carfully clamp one of the rad hoses using a couple of pieces of wood and a wood clamp to eliminate damage and see if it heats up. Of couirse remove or really loosen up the waterpump belt as you now have no coolant bypass circuit. If it does heat up than somehow or other the coolant is getting around or through the thermostat when it should not be. I do not think any other possibilities exist really other than above. Remember some mention that should be in archives about corrosion in thermostat neck area but thought problem caused was overheating. Would not hurt to pull themostat and put in a pan of water with a thermometer to see what temperature it opens at. It is possible to get a bad new one. If car is the same though it is a long shot but should be checked .Have a look for any major corrosion in area perhaps letting coolant get around the thermostat when your in there. A really long shot and impossible on most waterpump designs anyways is the impellor on the pump backwards. The effects produced if this where so are unknown to me but just verify flow direction is right as you are probably getting exasperated by now mind the cold air from a poor heater.

As I posted above I did use a infared thermometer on the head after a 30 minute drive last night... 130* F ... interior gauge read just over 50*C.
No my heater is not warm.. it is semi/barley warm... just enough to knock the chill off the cabin. The motor is not getting warm and thus I have very little heat.
I will try a new t-stat today.
No corrosion in the t-stat housing either.. I checked it out during the block heater install the other evening. I can rule out the impellor being on backwards too.. The previous water pump gave me the same temps as well... gotta be thermostat related.

I still appreciate all suggestions...

small update...

I pinched off both the upper and lower hoses tonight and let the car idle for 1 hr. Outside temps 25*f
results=

block and head temp 134*f
Temp gauge on cluster 55*c

This car will never get warm


This rules out the thermostat so I don't know what to do now. I was thinking I could haul a generator around in my trunk and run my block heater all the time:)

seriously... anyone have any suggestions?

well
 

idling it wont make any heat. the engine has to be working to make heat. i am with craig. get another stat. installed with disc down?

good luck.

tom w

Disc down?.. not sure of the meaning ... my t-stat goes in horizontal from the front ( see pic)... when I took it out the t-stat the disc was toward engine?

is this correct?
I appreciate you guys hanging in with me on this... I am determined to find the cause.

sorry
 

i must have forgotten the correct way that it sits. in your case i suspect it is disc toward the engine. if it is in backwards it wont work, but i think it will overheat. but that may have been in the summer. it definately wont work correctly if wrong. i checked my chilton. disc toward the engine looks correct.

again sorry to confuse the issue.

tom w

This manual shows the direction of the thermostat:

http://skinnerbox.steaky.org/Service/W123/w123CD2/Program/Engine/615/20-110.pdf

I don't have any better ideas.:confused:

[QUOTE= in your case i suspect it is disc toward the engine. if it is in backwards it wont work, but i think it will overheat.
tom w[/QUOTE]

I have it in right guys.. thanks ... funny thing.. as I said this motor won't overheat for anything... after clamping off the lower and upper radiator hoses completely and ildle for 1 hour.. the temp gauge did not go over 135*f

why dont you try driving it up
 

a hill with the hoses clamped off?

tom w

When I took our new tdi diesel back to dealer for low heat output a few years ago they told me the poor heater was partially the fault of synthetic oil. Well whatever it was it does not even come close to the older vw diesels as certain older examples would possibly burn your skin they were that hot. The heated seats are a neccesity in the tdi. I agree at idle most the car diesels I have had experience with do not make a lot of heat. Although the 240 is by no means the worst. If you clamped off both rad hoses and still did not rise in temperature though I would expect the heater core with a fan running could keep temperature down all by itself at the fans top speed So the only things left as it is substandard heat wise in comparison to my 24ds is the injection timing and perhaps the oi; cooling feature. If fuel injection is quite late less block heat would be generated in my opinion and chain stretch will make it late. How is your car for power? engine would possible be a little quieter than some with late injection as well. Does it start pretty good cold? Worth checking in my opinion but others may think otherwise and I could be wrong. Also remember the oil cooler is thermastatically controlled as well and if oil thermostat is constantly open might do it. It is located in the filter container I believe but not sure. Find out at what temperature it is suppose to open and if your oil cooler rad is warm or hot under that temperature you may have it. Where else is there left to look anyways?:D The heat is going somewhere or is not being made. Since the 240d does not burn more than one litre per hour at idle and part of that is converted to mechanical energy you do not have a lot left if a fault exists like one of the above to lessen it.

Look about the middle of the pictorial and you will see the proper orientation of the t-stat.

http://dieselgiant.com/thermostatreplacementandmodif.htm

Did you fix this?
 

bennett, did you fix this problem?? My 1982 240d is doing something similar. Everything seems to be working in the cooling system, I have a working t-stat, but the temp gauge says around 55-60 degrees. Also, the cabin heater is only working on occassion.

I'd be very interested to see if you fixed it!

Thanks.

After much investigation I have decided that these could have been an air cooled engine.:)

I pinched off both upper and lower radiator hoses and it still would not heat up. New stat installed correctly.
Thats on the freeway at 70mph on a 35* day,. I used a infared heat gun on the head after a 20 mile run at 70 mph and it read 109*f :confused:

I dont think these little motors can generate the heat needed to bring it up to 90*c in the winter.

I don't think pulling the fan would help either. I parked mine until it warms up.
My good friend has a 240 and if it gets 50* inside were lucky on a winter day.

They just don't generate heat!...

don't worry about it and drive it. My guess is most western 240s at higher elevations and colder temps all suffer the same .
maybe I'll take a poll.


bennett

My 240D (at almost 6000 feet) warms up to 80C within about 5 minutes and stays there regardless of ambient temperature. It has plenty of cabin heat, even with below 10F ambient temps. I don't know why some of these cars run too cold, but it's not normal and it can't be good for the engine.

What I think I'm discovering is that it the gauge, and nothing else, that's the problem. In the 240d there seems to be a problem where the gauge will just go up to 60 degrees, instead of 90 degrees, where it should be. BUT, the temperature actually is 90 degrees.

I think that the heat in the cabin is actually a different issue for bennett. I don't know, but I've discovered a couple other folks with this exact issue of the gauge being at 60 degrees, and they replaced their instrument cluster and now the temperature problem is "fixed."

As for the heat in the cabin, it seems like that might be the aux water pump -- I'm going out to check mine right now.

Does your 240D have a aux. pump?

Well, as it turns out, NO -- it doesn't have an aux water pump!! Pretty funny. One thing, though, is the fan behind the radiator is going all the time. Is that right??

Yes, that's correct. The 240D doesn't have a clutch on the mechanical fan.

So, the question is, where would be the connection for the blower for my cabin fan -- it definitely goes on and off when I go over bumps. Also, 99% of the time when I start the car the fan works, but then it stops after about a minute, and then it's a gamble as to when it is on.

Thanks a lot.

Did anybody ever get to the bottom of this issue? My 240 does the same thing. I have the water pump and thermostat out to be replaced now. The thermostat looks fine, the water pump was leaking though.

It has to be t'stat
 

The only thing that controls the temperature of the engine is the thermostat. I've removed many thermostats that where closed yet the engine was running cold, mostly VW 1.9TDi's. In 8 thermostat replacments, i've had 2 faulty, weak parts. No point messing around looking for other possibilities, I simply pull the housing and get another and hope it works this time ! You can get 'weak' thermostats.

Thats why somtimes when building an enine I will re-use the original thermostat if it was working correctly. A new thermostat is hit or miss in my opinion ! I would almost bring glow plugs into this same category, the occasional new g'plug will be faulty, but very rare to be honest !

An idling direct injection diesel will take forever to warm up, but an IDI isnt as bad, and under load an IDI warms up pretty quick, no matter who its manufactured by. IF another thermostat doesnt cure it, do what you where doing. Cover the rad and put it under heavy load. Lug it down and labour it a bit. And if its still not making heat, stop that quick because it must be a temperature sender problem and you dont want to blow the head gasket.

Where it a DI it would be more understandable but its not a direct injection so under load it should be making pretty good heat.

I wouldnt let this go. A cool running diesel will die an early death. It will sweat internally, sludge up, collect contamination that its unable to boil out of the oil and glaze the cyliners due to insufficient combustion temperatures and incomplete burn (washing). Very important of course.

Good luck and let us know what you find.

DM

Ok Dieselmonkey.... if its the stat...splain this to me?

I pinch off the lower and upper radiator hose with some carpenter clamps..

run her up to speed and still no heat...how could it be the stat?

I replaced the stat and cardboarded the radiator .... and still no heat !

bennett
 

are you running it up to speed on the road or sitting still?

tom w

Mine didn't heat up all the way on a 350 mile trip. :eek: I'll let you know how it works when I put it back together.

Drove it about 25 miles at different speeds, mostly 50 ish...

jumped out with my infared thermo heat gun and got 109* on the head:confused:

I'm willing to try anything........remember this car on a 100* day will barley reach 90*c on a uphill drive at 4500' elevation

Take out the thermo and check it for operation in a pot of water with a thermometer . If you read much on this site you will find that many a new out of the box thermostat is bad.
JOHN M

New thermo works fine .. tested in pot before install. Old wrorks just as well. Think about it. My carpenter clamp became the thermostat when I pinched off the hose. Still no heat.. very little change observed.

The only thing I have not done is remove the fan blade ...maybe that's next!

I dont think the fan has that much effect when the thermostat is closed, does it? If it does I wonder if installing the fan clutch off of a 617 engine would help.

240D too Cool..check my theory?
 

As a few have read and helped... summary... I just cannot produce any heat out of the motor over 130*F
Long story short I changed and pretty much tried everything but parked it till spring.

I have a new theory on what the problem might be...?

I always felt a little low on power compared to my buddies 240d so I advanced the injection a little and got what I thought was significant increase. Still not as fast as his car but much better for me. I used the bubble method ( blow in the tube) tpo what I felt was to spec.
81 240D 130k miles , great compression, well taken care of car by po. Always serviced and valve adjust done recently.

My question..

could the IP timing be off so much that I am losing heat and power thru compression or exhaust stroke as to not have the complete cumbustion at the right timing? ... hence the power goes out the exhaust .. does this make sense to anyone?


thanks

bennett