New radiator, new water pump, new belt, new idler pulley, spring, damper/shock and my 1995 E300D is still running hot.

This has been interesting so far but now it's just frustrating. (ever felt that?)
I thought I had this overheating issue solved when I pulled out the dual fan assembly and undid the cover to find 17 years of bugs and debris clogging up the entire bottom of the radiator and condenser. Literally over a quart of junk wedged in there. Miraculously I didn't break any of the plastis push tabs that mount the fan cover, but that was the only good news!
I cleaned everything and installed the new "Behr" radiator made in SouthAfrica. Dealer wanted $695 and I found this "OEM" for $127. It looked pretty good so, after installation I went for a test drive expecting a successful repair and the engine temp is still way higher than it should be it was aprox. 115-118 Deg. Centigrade. It was rather cool today when I went for a drive about 76 Deg F. and still that temp with heater on full it went down to 100 Deg. C, still too high.
This problem started after I did the delivery valves on the Inj. pump and put in new glow plugs. The wiring harness is sooo brittle that maybe I caused a short somewhere?
Any suggestions?

A couple of fairly easy suggestions to eliminate some possible causes.

1- Is the thermostat working properly? You can pull it and do a quick test by putting it in a pot of water and heating it until it starts to open. Or run it without a thermostat as a test.

2- Is the gauge reading accurately? You can use a non-contact thermometer to double check. Or possibly swap in a new sensor, preferably a known good one.

3- Is the wiring good? Can you run a wire from the sensor directly to the gauge?

That would be a good start to eliminate some important variables.

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

With the bypass thermostat design the car will run hot without a thermostat in hot weather.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Did you start with a cooling system pressure test? Have you done one since the cooling system renovation you described?

Are you seeing any coolant in the oil or oil in the coolant?

Have you checked ignition timing?

Also, as Tom said, don't get the idea to remove the thermostat altogether.

Hope this rambling helps in some way.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

If your wiring is bad then I can bet the gauge is not showing correct. The engine temp sensor is combined with the glow plug control temperature sensor, Its buried under the intake manifold but you can test it without removing it, the disconnect plug is a 4 pin square plug near the glow plug controller, it should have 4 wires, 1 brown (ground), 1 blue (HVAC eng temp sensor), 1 white (glow plug temp sensor) 1 green or something (display gauge sensor). Test the gauge wire for shorting and stick a 60 ohm (need to confirm) resistor in the body side and see the gauge, it should show 100*C. If it is then your gauge and body wiring is good. Test the sensor and its wiring. Or best get a IR thermometer and check the actual engine temperature at the cylinder head.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Thanks for the advise,
I pulled the thermostat and used the boiling water and it opens fine at about the right temp from what I could check.

Don't have a known good sensor to test with but I think I'll just buy a new one.

The wiring is CRAP! incredibly brittle.

Thanks for the info,
The car will run hot without the thermostat? I didn't know that. I just pulled it out to test the temp opening. On my engine 606 diesel there is only a straight connection on the thermostat housing, one hose out. Will this design make it overheat without a thermostat inline. I don't understand, but I will defer to you guys expertise. Shoot! and I was just ready to start it up and test...oh well.

Thank you for the suggestions,

1. did not do pressure test...will do.
2. no coolant in oil or oil in coolant.
3. it's a diesel and timing was not changed.
4. HMMM. I didn't know that was the case. Just pulled out Thermostat to check and wanted to start it up...
5. Larry, what type and gauge of wire would you use to construct a glow plug wiring harness? Is there special wire that will stand up to engine bay
temperature better than others?

IR temperature "gun" gauges where you point the laser at a point and itll show temp--can be had daily cheap (harbor freight, etc). I recommend picking one up and checking different components for hot/cold spots (which will pinpoint flow) as well as double checking your temp gauge in the car. Not a bad little thing to have in the toolbox either.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

the bypass design is cast into the thermostat/waterpump housing. - You should check the wiring for shorting, I am guessing its a wiring fault - specially if you say its falling to pieces.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Thanks, that's great advice!
Buried is the right word! I remember that plug and there is NO WAY I can get my hands in there without taking of the crossover intake manifold, and maybe not even then. I remember it did have 4 wires and the dealer parts guy told me it was a fuel idling circuit temp sensor (I'd never heard of that before) . I'll try to use some long needle nose pliers and disconnect it. Hopefully, I can get it out to work on.
Harbor freight IR thermometer might be a good way for me to go.

If you are familiar with the wiring on these, perhaps you can tell me what type, gauge etc.. to use in repairing/re-wiring this glow plug harness? I have never seen a wiring harness that is so brittle.

Thanks, that's probably what I'll have to do.

Non-Contact Infrared Thermometer with Laser Targeting

Item #96451





Only:$59.99
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My suggestion was based on the general design of engine thermostats.

It shows the importance of first-hand knowledge of specific design criteria for individual engines... and also the incredible resource that these forums are for that kind of information.

Thanks Tom for the quick correction and clarification.

Hopefully the other suggestions were ok

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Do you have the right pressure cap in place? Is it in good shape? Pressure testers usually have a fitting to test the cap as well. 603s use a 1.4 bar cap compared to the more common 1.2 bar cap. 606s might have the same spec.

Sixto
87 300D^2

Thx for the info,
The washer doesn't look that great, I will get a new cap from the dealer and check spec on bar recommendation.