High temperature on '79 528i

carlsturm · Post by **carlsturm** » Tue Jun 28, 2011 10:34 am

hi guys,
My528i warms up very slowly and after 15-30 minutes of driving the temperature gauge climbs to the last notch before the red area. Here's what I know:

- radiator fan is working
- there is sufficient coolant
- there is no coolant in oil

Do you have ideas on what is causing this?

How difficult is it to get to the thermostat?

(I need to buy a service manual)

thanks in advance,

carl

Lenny D. · Post by **Lenny D.** » Tue Jun 28, 2011 11:44 am

If your engine warms up slowly and then steadily climbs into the 'danger zone', you probably have a radiator issue.

A service manual will show you the thermostat is easy to access, but they are designed to fail in the open position, a nuisance in the cold of winter with the cooling system producing no heat. I would not look there first.

carlsturm · Post by **carlsturm** » Tue Jun 28, 2011 12:02 pm

thx Lenny

Lenny D. wrote:If your engine warms up slowly and then steadily climbs into the 'danger zone', you probably have a radiator issue.

A service manual will show you the thermostat is easy to access, but they are designed to fail in the open position, a nuisance in the cold of winter with the cooling system producing no heat. I would not look there first.

GripGreg · Post by **GripGreg** » Tue Jun 28, 2011 1:25 pm

I's not good to get that hot!
The thermostat is just above the fan belt pulley in the middle & at the front of the motor. It has the bleeder valve sticking out on top. The factory one has a slotted head for a screwdriver, the upgrade looks like a bolt.
I always try to start small/cheap & go on from there.
Put your rear wheels in the lowest part of a driveway with the front end being higher. Warm up the motor til the needle is at the half way spot; turn the motor off. SLOWLY open the bleeder valve, maybe a full turn, or til you see water or bubbles slowly come out. If water/coolant comes out with no bubbles it's properly bled & full; re-tighten, but not too[/i] tight & start the motor to double check if the thermostat is open, by slowly removing the reserve coolant tank top with that same rag. If coolant is moving nicely, the thermostat is open & operating properly. If it isn't moving you may have a bad thermostat which will overheat the motor.
The fun thing about this is, it can be done at home with a screwdriver or pair of pliers.
First, a small squirt of WD-40 on the bleeder valve will help. While at the auto parts store buying WD-40, get a large bottle of Prestone anti-freeze, it IS coolant, differant word. Don't add water, add coolant. Leave about 2 inches of air space above the coolant in the resevior. Don't fill it up.
Ask the P/O when the coolant was drained & re-placed. It should be re-placed every 2-3 years regardless of the mileage.
If I missed anything, the big dogs will chime in.
Good luck & jump on this RIGHT NOW! Greg

carlsturm · Post by **carlsturm** » Tue Jun 28, 2011 2:10 pm

Thanks GG. (btw, I consider you one of the 'big dogs')

GripGreg wrote:I's not good to get that hot!
The thermostat is just above the fan belt pulley in the middle & at the front of the motor. It has the bleeder valve sticking out on top. The factory one has a slotted head for a screwdriver, the upgrade looks like a bolt.
I always try to start small/cheap & go on from there.
Put your rear wheels in the lowest part of a driveway with the front end being higher. Warm up the motor til the needle is at the half way spot; turn the motor off. SLOWLY open the bleeder valve, maybe a full turn, or til you see water or bubbles slowly come out. If water/coolant comes out with no bubbles it's properly bled & full; re-tighten, but not too[/i] tight & start the motor to double check if the thermostat is open, by slowly removing the reserve coolant tank top with that same rag. If coolant is moving nicely, the thermostat is open & operating properly. If it isn't moving you may have a bad thermostat which will overheat the motor.
The fun thing about this is, it can be done at home with a screwdriver or pair of pliers.
First, a small squirt of WD-40 on the bleeder valve will help. While at the auto parts store buying WD-40, get a large bottle of Prestone anti-freeze, it IS coolant, differant word. Don't add water, add coolant. Leave about 2 inches of air space above the coolant in the resevior. Don't fill it up.
Ask the P/O when the coolant was drained & re-placed. It should be re-placed every 2-3 years regardless of the mileage.
If I missed anything, the big dogs will chime in.
Good luck & jump on this RIGHT NOW! Greg

GripGreg · Post by **GripGreg** » Tue Jun 28, 2011 6:29 pm

WOW! No, No, No. But thanx; I finally found someone with a smaller shade tree than me?!
You just happen to hit on a coupla subjects I know a lil somethin' about.
BTW, Lenny is a big dawg!
Did you check out the differant Cars of the Month? Kool, huh?

GripGreg · Post by **GripGreg** » Tue Jun 28, 2011 6:56 pm

Since Lenny said that, I thought of somethin' else.

Warm 'er up to half way, turn 'er off again & feel the radiator with your bare hand in between the fan blades at differant spots. If it's real warm in some spots but cold in others, the radiator is plugged up.
Have it 'rodded out'. That's the term you use at the radiator shop to act like you know what you're doin'.

If that's the case, ask them to install the new hoses that you buy from the parts store. If they balk, I'll understand, they're not in the installation biz, but it doesn't hurt to ask. Don't buy the accordian looking hoses either. (for some reason) Make sure they match the old hose curves. They don't have to be exact, but close.
I've even bought hoses that match, but, are too long. Guess what I did.
If you can't guess, ask me & I'll tell ya later!
That was a test.

Back under my small shadetree.

carlsturm · Post by **carlsturm** » Tue Jun 28, 2011 7:02 pm

y, There are some beautiful cars on Cars of the Month.

GripGreg wrote:WOW! No, No, No. But thanx; I finally found someone with a smaller shade tree than me?!
You just happen to hit on a coupla subjects I know a lil somethin' about.
BTW, Lenny is a big dawg!
Did you check out the differant Cars of the Month? Kool, huh?

socalfiver · Post by **socalfiver** » Fri Jul 08, 2011 9:29 am

A note on replacing hoses-

If the curves of the replacement hoses do not *perfectly* match your originals, make sure to verify all clearances between pulleys and hoses after installation, with the engine fully warmed.

I had purchased a low-grade (non-accordion) replacement lower hose at AutoZone. The shape was close to, but not exactly the same as, the original. It expanded when warm, and rubbed against the fan pulley. It cut right through and let all my coolant out at 80mph. By the time I pulled over, my car had overheated so badly that I was stuck in Las Vegas for 11 days having my head milled and installing a new head gasket in my buddy's driveway.

I purchased a more expensive German replacement hose, which is much nicer quality rubber and does not expand when warm.

carlsturm · Post by **carlsturm** » Fri Jul 08, 2011 11:02 am

Phew --- thanks for the info.

socalfiver wrote:A note on replacing hoses-

If the curves of the replacement hoses do not *perfectly* match your originals, make sure to verify all clearances between pulleys and hoses after installation, with the engine fully warmed.

I had purchased a low-grade (non-accordion) replacement lower hose at AutoZone. The shape was close to, but not exactly the same as, the original. It expanded when warm, and rubbed against the fan pulley. It cut right through and let all my coolant out at 80mph. By the time I pulled over, my car had overheated so badly that I was stuck in Las Vegas for 11 days having my head milled and installing a new head gasket in my buddy's driveway.

I purchased a more expensive German replacement hose, which is much nicer quality rubber and does not expand when warm.