1988 325 cabbie over heat or dodgie instruments??? NEED HELP

Thu Jun 16, 2011 9:00 pm

how do folk's just bought a 325 cab ,the car was liein up for 2 years and had 3 bolt's rang off on the exhaust manafold so was blowin quite bad and instruments not workin right ,petrol guage ,rev's & mpg dont read ,mph seem's to work fine so dose the temp!! I just got the car back from my mechanic today after gettin new studs & gasket in the exhaust manafold, so i got to take my first spin in her & found after 20 mins the temp guage slowly rose into the red!!!!! their is coolent in her & no scum under oil filler cap!! oh ya and when i turn on the headlights the temp guage jump's up by a extra 20% & when i turn the lights off it go's back down!

Can anyone help ,whats wrong with the instruments???
And is the car overheatin or just down to dodgie instruments??

help would be much appreciated,thanks

Thu Jun 16, 2011 11:30 pm

Temp gauge goes to the red in normal driving, or in traffic/left to idle?
There is a 7mm brass nut on the back of the instrument cluster, directly behind the temperature gauge. Try tightening this for the jumping needle part. Tighten the one behind the fuel gauge as well, while you're there.
Be very careful running this engine until the faults are identified - you won't overheat a M20B25 head many times without it cracking.

Fri Jun 17, 2011 12:26 am

I agree, tighten the nuts. Best way to verify temp is the use of an infra red temp gun. Point it at the thermostat housing and hoses, should be approx 80 C. Getting too warm is slow traffic is usually the fan clutch mounted to the engine fan. They loose their ability to lock up at higher temperature to force air thru the radiator.

Fri Jun 17, 2011 12:46 pm

as i said i just picked it up from my mechanic had to jump start it (no fuel and flat battery)so i headed straght for the petrol station ,keepin an eye on the temp (sittin nice at half way) so i pulled in for fuel( had to leave it runnin cos of battery) i know the guy their so he filled her up and gave her a quick wash for me(about 20 mins) .I jumped back in and saw the temp had just gone into the red!!!!!my house was a 1 min drive so i went on ,the temp came down a bit as i drove her ,got home and shut her down.

have i done damage????? any idea what caused this??????
is it anything got to do with liein up for so long?????

Fri Jun 17, 2011 2:16 pm

As grantorino said, it looks like the viscous fan coupling (so far). These cars don't have electric fans, the fan is run by a pulley on the front of the engine which has a "clutch" arrangement to make the fan spin properly when the engine is hot. If the clutch has failed (which they do every ten years or so) your fan still spins but doesn't really get up to speed.
Since the fan is only really needed when the car is stationary, you find that you overheat when stationary or moving in slow traffic.

However, overheating these cars can easily crack the cylinder head - so you need to get that temp gauge sorted out. Check the nuts and post back, I'm sure Brianmooore will take you ont the next stage of diagnosis. You'll probably need a multimeter pretty soon!

Fri Jun 17, 2011 2:58 pm

flashpat wrote:.... when i turn on the headlights the temp guage jump's up by a extra 20% & when i turn the lights off it go's back down!

Mine did this. Turned out to be a poorly corroded main engine earth strap - goes from the lower left side of the block to the left hand chassis rail. Undo both ends, clean up with wire brush/sandpaper, refit.

Martin.

Fri Jun 17, 2011 3:17 pm

Engine to body earth strap can cause problems like this, but on E30s the battery - terminal is connected to the body, not the engine block like on some other cars, and so carries the starter motor current as well. The slightest bit of excess resistance will badly affect the starter performance, so this is usually the reported problem, rather than any other side effects.
On six cylinder facelift E30s, a defective body to engine earth strap can have serious (as in insurance write off) effects, as there is a parallel earth path through the body of the oil level sensor via the brown/orange wire connected to it, to the brown/orange wire connected to the top of the RH suspension turret. This wire tends to get more than slightly warm if asked to carry the starter motor current, and severely damages the engine loom!