Phantom Overheating M20?

acroll80 · 04-17-2012, 10:12 AM

Hello to all E30 patrons! I Have been frustrated

for some time now with a possible overheating issue with my e30. Let me give a quick background of my situation. I have a 1989 325i coup that I have owned for seven years now. This thing is a trooper to say the least, I bought it with a spun rod bearing and basically did an entire lower end rebuild at that time. I have done all repairs and maintenance myself. I just finished a timing belt replacement a few weeks ago. Ever since then my temperature gauge creeps up to 3/4 in any driving situation unless Im hauling ass on the freeway, or if my heat is on full blast, or if I jump the high speed aux fan. It will stay at the 1/2 mark doing those things. So let me say that I have replaced the fan clutch, water pump, t-stat, v-belt, coolant cap, cleaned the radiator inside and out.
The system holds pressure, it heats up at a normal pace, heat works as it should. Ive bled the system many times over with no sign of air left in the system. There is no traces of oil in the coolant, no coolant in the oil, no loss of coolant, the exhaust appears normal (no coolant burning).
All my replacement parts are from OEM suppliers so Im not assuming that they are faulty. the only thing I can think of now is that the gauge is lying to me, and or sensor is bad, but Ive never seen or heard of that happening.
Thanks to all that read this post and any help or suggestions would be greatly appreciated.

protomor · 04-17-2012, 10:25 AM

you probably replaced it with a higher temp Tstat. Get a real temp gauge and take a look at what it's doing. If it's stable, you're fine. Stock gauges aren't linear FYI.

acroll80 · 04-17-2012, 11:40 AM

I put in a 75 deg. t-stat, the previous was 80 deg. so if I monitor with another temp gauge what should the average temp be reading at normal operating conditions?

protomor · 04-17-2012, 11:53 AM

usually I see cars sit anywhere from 180 to 190. Anything over 200 would be concerning. 210+ is dangerous. 250 is bad news bears. I've hit that a few times lol.

acroll80 · 04-17-2012, 12:10 PM

Thanks for the insight! I will give that a try. I might change out the temp sensor and gauge as well just for good measure. I have a ton of them laying around.

meh powered · 04-18-2012, 09:25 PM

Try tightening hose clamps maybe there is a little leak getting in. Happened to me once. But got a lot hotter.

Nutzy · 04-18-2012, 09:34 PM

My old 84 323i and Mum's E34 520i both had a similar ailment; the earth on the temp gauge itself. They both would flick from a regular half way point on the gauge to 3/4. I chased this phantom overheating in my 84 for ages until one day I saw the gauge flicking from 1/2 to 3/4 and back again.

Just sayin', make sure it REALLY is getting too hot before chasing this one. If you can, grab a laser temp temp gun and check it.

meh powered · 04-18-2012, 10:05 PM

^^^that

winfred · 04-18-2012, 10:23 PM

make sure the pisser tube from the radiator to the tank is free flowing, when you rev it with the cap off you should be able to see a stream, if this is plugged the system won't function properly and will eventually overheat. when the gauge is above normal smack the piss out of the dash on that side of the cluster and see if it moves

Nutzy · 04-18-2012, 10:29 PM

^^Haha, yep, Mum got the shits with hers and smacked the dash. It obediently went back to 1/2!

04-17-2012, 10:12 AM	#1
acroll80 Noob [Needs 25 to Sell] E30: 1989 325i, 1990 325is Location: Los Angeles, California Join Date: Dec 2007 Posts: 8	Phantom Overheating M20? Hello to all E30 patrons! I Have been frustrated for some time now with a possible overheating issue with my e30. Let me give a quick background of my situation. I have a 1989 325i coup that I have owned for seven years now. This thing is a trooper to say the least, I bought it with a spun rod bearing and basically did an entire lower end rebuild at that time. I have done all repairs and maintenance myself. I just finished a timing belt replacement a few weeks ago. Ever since then my temperature gauge creeps up to 3/4 in any driving situation unless Im hauling ass on the freeway, or if my heat is on full blast, or if I jump the high speed aux fan. It will stay at the 1/2 mark doing those things. So let me say that I have replaced the fan clutch, water pump, t-stat, v-belt, coolant cap, cleaned the radiator inside and out. The system holds pressure, it heats up at a normal pace, heat works as it should. Ive bled the system many times over with no sign of air left in the system. There is no traces of oil in the coolant, no coolant in the oil, no loss of coolant, the exhaust appears normal (no coolant burning). All my replacement parts are from OEM suppliers so Im not assuming that they are faulty. the only thing I can think of now is that the gauge is lying to me, and or sensor is bad, but Ive never seen or heard of that happening. Thanks to all that read this post and any help or suggestions would be greatly appreciated. __________________

04-17-2012, 10:25 AM	#2
protomor Senior Member E30: 1987 325i, 1989 325i M50T Location: Northern VA, USA Join Date: Aug 2005 Posts: 14,003	you probably replaced it with a higher temp Tstat. Get a real temp gauge and take a look at what it's doing. If it's stable, you're fine. Stock gauges aren't linear FYI. __________________ Status: LS2 swap

04-17-2012, 11:40 AM	#3
acroll80 Noob [Needs 25 to Sell] E30: 1989 325i, 1990 325is Location: Los Angeles, California Join Date: Dec 2007 Posts: 8	I put in a 75 deg. t-stat, the previous was 80 deg. so if I monitor with another temp gauge what should the average temp be reading at normal operating conditions? __________________

04-17-2012, 11:53 AM	#4
protomor Senior Member E30: 1987 325i, 1989 325i M50T Location: Northern VA, USA Join Date: Aug 2005 Posts: 14,003	usually I see cars sit anywhere from 180 to 190. Anything over 200 would be concerning. 210+ is dangerous. 250 is bad news bears. I've hit that a few times lol. __________________ Status: LS2 swap

04-17-2012, 12:10 PM	#5
acroll80 Noob [Needs 25 to Sell] E30: 1989 325i, 1990 325is Location: Los Angeles, California Join Date: Dec 2007 Posts: 8	Thanks for the insight! I will give that a try. I might change out the temp sensor and gauge as well just for good measure. I have a ton of them laying around. __________________

04-18-2012, 09:25 PM	#6
meh powered Member E30: 1984 318i Location: nc Join Date: Feb 2012 Posts: 45	Try tightening hose clamps maybe there is a little leak getting in. Happened to me once. But got a lot hotter.

04-18-2012, 09:34 PM	#7
Nutzy Senior Member E30: '89 327 Turbo Location: Oz Join Date: Oct 2004 Posts: 1,725	My old 84 323i and Mum's E34 520i both had a similar ailment; the earth on the temp gauge itself. They both would flick from a regular half way point on the gauge to 3/4. I chased this phantom overheating in my 84 for ages until one day I saw the gauge flicking from 1/2 to 3/4 and back again. Just sayin', make sure it REALLY is getting too hot before chasing this one. If you can, grab a laser temp temp gun and check it. __________________ *********************** -Pete My current E30 turbo build thread *********************** Last edited by Nutzy : 04-18-2012 at 10:28 PM.

04-18-2012, 10:05 PM	#8
meh powered Member E30: 1984 318i Location: nc Join Date: Feb 2012 Posts: 45	^^^that

04-18-2012, 10:23 PM	#9
winfred Contributing Member E30: 91 328is m20b28 with a hair drier and some other goodies Location: baton rouge loserana Join Date: Jan 2006 Posts: 3,782	make sure the pisser tube from the radiator to the tank is free flowing, when you rev it with the cap off you should be able to see a stream, if this is plugged the system won't function properly and will eventually overheat. when the gauge is above normal smack the piss out of the dash on that side of the cluster and see if it moves __________________ Political Correctness is a doctrine, fostered by a delusional, illogical, liberal minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

04-18-2012, 10:29 PM	#10
Nutzy Senior Member E30: '89 327 Turbo Location: Oz Join Date: Oct 2004 Posts: 1,725	^^Haha, yep, Mum got the shits with hers and smacked the dash. It obediently went back to 1/2! __________________ *********************** -Pete My current E30 turbo build thread ***********************

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode