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  #1  
Old 08-04-2015, 01:36 PM
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Location: NorCal
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New radiator/runs hot

Looking for a little help...
1983 300cd turbo.

Recently did:
-install new nissens radiator
-new hoses
-new thermostat. Arrow up
-new water pump
-new drive belts
-drained old green coolant from block
-poured in blue mb coolant through upper hose.
-new overflow tank
-new temp sending unit on block

Temp usually 90-100C
Intermittently it will drop to around 85

This is at freeway speed
In stop and go it may stick closer to 100

Any ideas?
I've already changed the stat 3 times
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  #2  
Old 08-04-2015, 01:38 PM
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The rise and drop in temp do not seem to correlate to the load on the engine.

Heat works.
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  #3  
Old 08-04-2015, 01:44 PM
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Could this be the culprit?

Image from http://www.peachparts.com/shopforum/attachments/diesel-discussion/92834d1307727706-diy-water-pump-bypass-hose-replacement-om615-616-617-1152000058_drthjutdh.jpg.

Block to water pump bypass pipe
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  #4  
Old 08-04-2015, 01:55 PM
Rogviler's Avatar
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I'm interested in this as well, since I also just did all new cooling system parts (Nissens radiator included) and that's exactly what mine does.

Before I did all that it never got above 80C, how about yours?

-Rog
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  #5  
Old 08-04-2015, 02:05 PM
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Same. Used to run a bit above 80. Consistently.

And that's when my ac used to work.

The compressor belt has since been cut while I sort out
Other maintenance issues.
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  #6  
Old 08-04-2015, 02:11 PM
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-I had a similar issue when I did just a coolant change.

Did you guys make sure to fill it with the front end up high (on ramps) and through the upper radiator hose? Could be an air pocket in there.

This fixed my issue. Coolant back at mostly 80C all the time unless hill climbing or highway speed then it creeps up just a little.

I did read on here that all Tstats for this car are not created equal. Read that OEM from the dealer has best results, but still could be faulty...
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  #7  
Old 08-04-2015, 02:16 PM
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I did get it up on ramps and filled upper house until coolant flowed through radiator neck.

3rd tstat was mb brand.
Installed with little arrow pointing up
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  #8  
Old 08-04-2015, 03:40 PM
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I'm guessing that there's air in there somewhere (my new song lyric!).

There's a cheating way to assure that you get all of it out that we used on R5 Renault's (The Le Car here in the US). Get a spare radiator cap and cut the middle out of it. Get about a 1 foot length of appropriately sized tubing (we used 1 1/2" EMT conduit). Braze or solder that to the radiator cap such that the tube sticks up. Get a good sized steel funnel and braze or solder that to the top of the tube such that you have a reservour to hold the coolant (a trick here is to add the antifreeze to the lower radiator/block first and add pure water with the rig in place - that way any spills are just water). Anyhow, start the car and do the typical burp the radiator routine with the rig in place.

This rig assures that you have a head on the coolant so that any bubble has a higher place to which to escape. With the R5 it was a real PITA but they did have an air bleed so you could release air from a pocket (seems like it was the heater core) as you did the ritual.

These days there are pressurized systems available (my buddy has one at his professional shop) that force the air out - his uses a slight amount of compressed air. But the system described does work and costs little.

Dan
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  #9  
Old 08-04-2015, 04:19 PM
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Quote:
Originally Posted by Dan Stokes View Post
I'm guessing that there's air in there somewhere (my new song lyric!).

There's a cheating way to assure that you get all of it out that we used on R5 Renault's (The Le Car here in the US). Get a spare radiator cap and cut the middle out of it. Get about a 1 foot length of appropriately sized tubing (we used 1 1/2" EMT conduit). Braze or solder that to the radiator cap such that the tube sticks up. Get a good sized steel funnel and braze or solder that to the top of the tube such that you have a reservour to hold the coolant (a trick here is to add the antifreeze to the lower radiator/block first and add pure water with the rig in place - that way any spills are just water). Anyhow, start the car and do the typical burp the radiator routine with the rig in place.

This rig assures that you have a head on the coolant so that any bubble has a higher place to which to escape. With the R5 it was a real PITA but they did have an air bleed so you could release air from a pocket (seems like it was the heater core) as you did the ritual.

These days there are pressurized systems available (my buddy has one at his professional shop) that force the air out - his uses a slight amount of compressed air. But the system described does work and costs little.

Dan
so your rig does the same thing a spill free yellow funnel does?
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  #10  
Old 08-04-2015, 04:40 PM
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So pouring coolant into the top hose with the wheels up doesn't get the air out completely?
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  #11  
Old 08-04-2015, 04:41 PM
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Thought that was "the" best way...

Last edited by jabstick420; 08-04-2015 at 05:31 PM.
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  #12  
Old 08-04-2015, 10:37 PM
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Quote:
Originally Posted by jabstick420 View Post
Thought that was "the" best way...
I think the answer is "it might". But the cooling system is "open" with that hose off so it's not exactly in the configuration it will be in when the car is in service. R5s were a royal PITA to burp and after trying several techniques we hit on this and it worked.

No, it's not the same as jabbing a long necked funnel into the radiator opening - unless you were able to get a good seal between the inside of the radiator neck and the funnel tip. I suppose it's possible to get lucky and find a funnel that's JUST RIGHT and you were able to cram it in there JUST RIGHT - but we never had much luck with it.

The fabrication isn't very difficult and you'll have a tool for life. My radiator tank in Mutt is higher than the highest part of the engine's cooling system so I haven't needed to make one of these (the one we made for the R5 was left at my buddy's shop in MI). But if I had a tough one to burp you can rest assured I'd be brazing.

Dan
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  #13  
Old 08-04-2015, 11:27 PM
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Quote:
Originally Posted by Dan Stokes View Post
I think the answer is "it might". But the cooling system is "open" with that hose off so it's not exactly in the configuration it will be in when the car is in service. R5s were a royal PITA to burp and after trying several techniques we hit on this and it worked.

No, it's not the same as jabbing a long necked funnel into the radiator opening - unless you were able to get a good seal between the inside of the radiator neck and the funnel tip. I suppose it's possible to get lucky and find a funnel that's JUST RIGHT and you were able to cram it in there JUST RIGHT - but we never had much luck with it.

The fabrication isn't very difficult and you'll have a tool for life. My radiator tank in Mutt is higher than the highest part of the engine's cooling system so I haven't needed to make one of these (the one we made for the R5 was left at my buddy's shop in MI). But if I had a tough one to burp you can rest assured I'd be brazing.

Dan
I think "jabstick420" is talking about the spill free funnel, not a regular funnel:

http://www.amazon.com/Lisle-24680-Spill-Free-Funnel/dp/B00A6AS6LY/ref=sr_1_1?ie=UTF8&qid=1438745680&sr=8-1&keywords=spill+proof+funnel
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  #14  
Old 08-04-2015, 11:47 PM
dkr dkr is offline
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Try testing or replacing the radiator cap to make sure it pressurizes properly.

Dkr.
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  #15  
Old 08-05-2015, 02:53 AM
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The stock thermostat is not 80C so the engine will NEVER run 80C. I put an 80C thermostat in my 601 and I run between 80-90C while cruising around. On the highway I'm between 90-100, but that's at 75 uphill when it's 105 outside.

If the OE temp is 82 or 85C the car will never run cooler than that.
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