can I hurt the engine with low temps?

[FiveSpeedSquirrel]

My new-to-me E30 seems to have a problem with the coolant temperature. It never gets much past the hashmark before the halfway point, so it runs at around 30% warm. I think the thermostat may be stuck open. It still blows hot air in cold weather, so I don't think it's off by much.

I plan to have a maintenance weekend in which I'll do the timing belt, water pump, t-belt tensioner, and thermostat. But I can't do that for like 2 weeks. In the meantime, I have a few hundred miles of daily driving and even an autocross to partake in.

My question is, if I am giving the car plenty of time to warm up before I run it hard at higher revs, do I risk causing any engine damage or excessive wear at these operating temps? I figure that the oil will provide adequate lubrication even if the coolant is a bit colder than it should be. But any input would be appreciated, I don't want make my M20 sad :(

[hoveringuy]

Mine runs at the same temps. I won't even get past the 1/4 mark unless it's summer time. I approached 1/2 on the temp gauge stuck in traffic when it was 95 degrees out.

Be glad you're not overheating!

[NC325iC]

my car does the same thing with a brand new/hotter t stat even in 100 degree weather,

[FiveSpeedSquirrel]

Is this normal for our cars? I just want to make sure I'm not causing unknown damage... I know the engine prefers to run at a hotter temp. Unless it's just a problem with the gauge.

[Shoomakan]

You're fine, my car always run very slightly below the 1/4 mark if driven gently, but when floored HARD never gets to half temp.

M30's apparently run best at 1/4 temperature, so I'm happy. M20's, I don't know. But, like the guy said, be glad you're not overheating!

[Toms73NovaSS]

Most of the time engine temp is a result of what the manufacturer need to comply with emissions. As an example, I have a 1990 formula firebird and from the factory it came with a 220 deg thermostat. The reason for that was to promote more through burning of the fuel, it was definitely not a power mod! It basically is the same engine that was in my 73 Nova that ran a 170 deg thermostat, when emissions were not really all that big a thing yet. I have since put in a 170 deg stat in my formula and there is a noted difference in its performance in the summer.

With the BMW's I would think that the engine is efficient enough (emissions-wise) that the higher temps were not required to meet the gov. standards.

Just my $.02

[ldsbeaker]

M30's apparently run best at 1/4 temperature, so I'm happy. M20's, I don't know. But, like the guy said, be glad you're not overheating!

Well that explains my 535is' action...

[jlevie]

Normal position of the needle with a 75C thermostat is barely past the "1/4" mark, rising to the mid mark in stop and go traffic in hot weather. With an 80C thermostat normal position is about half way between the first mark and the 12 o'clock mark, rising to the mid mark or slightly above in stop and go traffic in hot weather.

The usual signs of a stuck open thermostat are very slow warm up or the needle remaining below the first mark at highway speed.

From what you described I'm not sure that you have a problem. But I would recommend replacement of the thermostat & pump when you do the timing belt.

[-Javier-]

is it safe to run an e30 with out a thermostat?

[alpinaclone]

is it safe to run an e30 with out a thermostat?

I wouldn't, the thermostat also serves as a restrictor to coolant flow. With it removed the coolant may move to fast, causing it to not be able to do it's job as effectively. It may not be that big of a deal, but overheating is one of the biggest killers of these engines, and I would rather not chance it.

Matt

[nmlss2006]

Uhm, a question if I may: are we positive that M20s with stock thermostats are supposed to read lower than the middle and to fluctuate? I ask because it's the first time I hear anything of the sort. As to coolant moving too fast, I wouldn't be worried. That's not how heat transfer works.

[Ray Smoodiver]

my 2.7 runs at halfway all day everyday, never up or down. Only on very cold nights at highway speeds does it creep toward the 1/4 mark.

[nando]

Uhm, a question if I may: are we positive that M20s with stock thermostats are supposed to read lower than the middle and to fluctuate? I ask because it's the first time I hear anything of the sort. As to coolant moving too fast, I wouldn't be worried. That's not how heat transfer works.

yes - in fact, the fluctuation in the gauge was why BMW went to a "buffered" gauge that always read at 1/2 on the E36, because people were coming into service shops thinking their cars were broken. the solution? replace a working gauge with a worthless one (and I don't think new BMWs even have a clt gauge!).

[nando]

Uhm, a question if I may: are we positive that M20s with stock thermostats are supposed to read lower than the middle and to fluctuate? I ask because it's the first time I hear anything of the sort. As to coolant moving too fast, I wouldn't be worried. That's not how heat transfer works.

yes - in fact, the fluctuation in the gauge was why BMW went to a "buffered" gauge that always read at 1/2 on the E36, because people were coming into service shops thinking their cars were broken. the solution? replace a working gauge with a worthless one (and I don't think new BMWs even have a clt gauge!).

[DaveSmed]

Uhm, a question if I may: are we positive that M20s with stock thermostats are supposed to read lower than the middle and to fluctuate? I ask because it's the first time I hear anything of the sort. As to coolant moving too fast, I wouldn't be worried. That's not how heat transfer works.

Thats not how engines work though, they like to run at a specific temperature, which is why you dont beat on a cold engine. Without a thermostat, it is likely you will over-cool the car.


As far as gauge accuracy goes, remember: That thing runs through six 20 year old connectors, goes through the failure prone SI board, etc. It is not what one would consider a scientific measurement. Think of it more as an idiot-light plus, if it's not where it normally is, theres a problem, and by how far off from where it should be gives an idea about the severity of the problem.