A little Heat Problem! [Archive] - Bimmerfest - BMW Forums

: A little Heat Problem!

10-27-2009, 08:51 PM
Hey, New to this Forum,
Have a 1990 E34 525i, Since i got it the water level for the Cooling system kept dropping low so ive been topping it up... but now its over heating and the Water level wont stay up keeps disappearing within minutes, seems to boil out through the Radiator cap at Extreme pressures, Is there a certain way to Bleed air out of this system?

Any help will be VERY helpful!!

Thanks heaps,
Ben from NZ!

10-28-2009, 03:09 AM
First check to make sure you do not havr a leak. And make sure you do not have a crack in the radiator, hoses or a crack in the expansion tank. Even without a leak, a Bad thermostat, fan clutch or waterpump can cause overheating.

For bleeding, follow the steps in the link below.


10-28-2009, 12:03 PM
Hey, New to this Forum,
Have a 1990 E34 525i, Since i got it the water level for the Cooling system kept dropping low so ive been topping it up... but now its over heating and the Water level wont stay up keeps disappearing within minutes, seems to boil out through the Radiator cap at Extreme pressures, Is there a certain way to Bleed air out of this system?

Any help will be VERY helpful!!

Thanks heaps,
Ben from NZ!

Regretfully, your symptoms are exactly those I would expect for a blown head gasket.:(
Check to see if you have any coolant in your oil or oil in your coolant, another sure sign. The reason you are seeing high pressures in the cooling system is that combustion pressure is leaking into it.:thumbdwn:

10-29-2009, 05:23 PM
If you replace the head gasket you need to be carefull if you do it your self!!!! the bolts have to be place back on and taken off in a zig zag removal and use a torque wench to place the head back on. other wise you are at risk of bowing the head and thats not good for the valves and pistons. its just a little tip not trying to be mean i know some shops dont do that! if im wrong about any thing just let me know!

10-30-2009, 07:15 AM
i just did the head gasket on my 1990 525. get the bentley service manual and it is a straight forward job. pelican has a complete head gasket kit has all the seals (valve guide, cam, inspection etc. ) you will have to replace the headbolts as they are stretched when torqued. the biggest problem i had was because of where the leak was and the car sat for a number of years, the intake manifold stud in the center became part of the manifold. it had to be drilled out to remove the intake. Also, make sure the cat is loose by the transmission bracket, it makes it alot easier to put the cat back on the manifolds. one other suggestion, change all the hardware. it is not that expensive and helps reassembly. you should also change the water pump, themostat and timing belt while your in there. good luck.

10-30-2009, 07:34 PM
I dont think is the Head Gasket as there is no huge pressures coming out of the cooling system just a Slow pulsing bubbling out of the radiator Cap plus there is no oil in the Radiator or Water in the Oil, Radiator, Hoses and Thermostat have all been replaced with brand new items over the last year, And once the car is warm and the Cooling Fan turns on there is a VERY rattley noise coming out from where the Water Pump is?

So my Guess is just another water pump and everything will be sweet,

Thanks for all the tips and help!

10-31-2009, 07:41 AM
A bad water pump wouldn't cause 'bubbling' or enough pressure for coolant to escape from the radiator cap. The rattling could be a bad water pump or your clutch-fan unit, but it could also be the water pump cavitating due to the air in the cooling system. I hope it isn't a head gasket, but that still sounds like the most likely cause.

10-31-2009, 01:30 PM
Oh Really? I thought that if there was no Water or Oil in either Radiator or Engine then the Head Gasket would be safe? Also the Rattling has only started since the Overheat, THere is no leaking or anything around the Engine

10-31-2009, 02:17 PM
If the head gasket fails between a cylinder and a coolant passage, then you may not get oil in the coolant, just gases. The oil/water mixing usually happens if a head gasket fails between an oilway and a coolant passage. I would check the water Pump and proably change it anyway if you don't know if/when it was last done. Change the Thermostat while you are at it. Hopefully it isn't the head gasket but I still can't understand how a water pump could overpressurise and draw air into the cooling system. Kiwi magic perhaps?!:D

10-31-2009, 08:19 PM
Haha nice glad you know im a Kiwi! wasnt too sure just how LARGE this Forum was...

True true sounds fair enough I guess, well the Water Pump has definately failed so ill replace that and see if i get anywhere, the headgasket was replaced last year as the head had a FULL rebuild

E36 Phantom
10-31-2009, 09:55 PM
Uhm.......what about a failing radiator cap? They are supposed to hold a certain pressure, and if they fail they won't hold that pressure as well. KISS - keep it simple, stupid.

11-02-2009, 09:53 PM
True true, thats what i thought... there is a slow pulse if i fill up the radiator then turn the car on, once its hot the water level goes up and down

HOW the HELL do you get the 32mm Nut off behind the Rad Fan?

11-04-2009, 10:40 AM
The 32mm nut has a Left-Hand thread so make sure you are trying to undo it in the correct direction. Best way is to get a long wrench (spanner!) and strike it with a rubber or hide mallet to loosen the nut. Pushing down on the drive belt between the pulleys may help add some friction to hold the water pump pulley still.

11-06-2009, 12:22 PM
Thanks lol **** ive gone too far, Undid the Pulley and took the belt off first... guess im putting things back together to undo the 32mm nut! what a pain the the ass, thanks anyway mate might stop me from droppin it into the dealer to get done

11-06-2009, 03:11 PM
How did you manage to get the pulley off without removing the fan/clutch assembly?:dunno:

11-07-2009, 10:00 PM
Sorry, I undid the Pulley so its sitting there between the Engine and Rad Fan thingy lol
Have it booked into the Mechanics though so their problem now! just want the car back on the Road

You seem to know alot about these E34's

Mine has VERY loud tappet noises coming from the Head which has had $8,500 spent on it from the previous owners trying to get rid of it

I have also found someone who has 2 engines to sell, both and 2.5 **TWIN CAM** but ones Vanos ($850) and one is Non Vanos ($900)

Would you recommend just trying to fix the Tappet noises or buy one of these engines?
Thank you for being such a help in this problem!

11-07-2009, 10:18 PM
I'm no expert, just a DIY car nut who has owned a few Beemers over the years.
How do spend $8500 on rebuilding a Head!!!
What year is your E34 and what engine do you have? Tappet noise is not uncommon but if it is really loud then there has to be a problem. Changing Engines seems rather drastic to cure a Cylinder Head problem. At most I would try to find another good head and swap that out first. Also, if you aren't already, I would recommend using a good synthetic oil such as Mobil-1 as this can certainly reduce valve clatter in some engines.

Do you know if the Camshaft was checked when the head was re-built? If the lobes were worn it is possible that the tappets have too much clearance and the hydraulic valve adjustment cannot take up the gaps. It is also important to make sure the tappet surfaces are in good shape as any pitting or cracking can lead to rapid wear and noise. Of course none of these things can be confirmed unless you remove the head, so maybe finding another servicable head to replace it while you sort out the problem wouldn't be a bad idea.

11-09-2009, 10:42 PM
$8500 NZD :) Yeah the family who owned it before me knew NOTHING about cars... so id say they were a little bit ripped off! And sorry a full engine rebuild not just the head, they changed pistons and gave it a bore

Yeah says on the receipt that the cam was machined and what not...

Only reason why I was concidering an engine swap is because im finding it hard to find people who are willing to part a head from a block, and wouldnt it be alot more powerful having a Twin cam engine from a newer model compared to an old Sohc from the 1990?

Back to the problem at hand, I got the Water Pump swapped out and thats eliminated the HORRIBLE noises but im having problems bleeding the air from the System, I read that you are supposed to fill it with water/coolant and leave the bleeding screws open till water is flowing continuously, but instead STEAM is just blasting out.... Gah no cure to fixing cars lol

11-10-2009, 06:38 AM
Quick cooling system bleeding process:

Run the car for a short while with both heater controls at full heat and until you feel warm coolant in the lower Rad hose (ie. Thermostat open).
Raise the front of the car onto ramps or park uphill on a slope.
Let car sit for 5-10 minutes.
Carefully loosen the Bleed Screw on top of the Rad to let air in the system slowly escape.
Top up coolant to correct level.
With the bleed screw slightly open, run the engine until at normal operating temperature.
Close Bleed screw when only coolant is coming out.
Park car on level ground, let cool completely and then top up coolant to normal level.

If after all this you are still getting steam out of the bleed screw then I fear my original diagnosis may be correct - blown head gasket:thumbdwn:

I'm sure a later engine swap is possible, but there are probably other changes required, not least the associated hardware for the VANOS system and a new engine ECU. I doubt the change would be worthwhile given the hassle involved. Besides, if your existing engine has been recently rebuilt why not stick with it and solve the head gasket problem - if that's what it is. It is not that difficult a job and I'm sure its a lot less costly than an engine swap.

11-10-2009, 10:13 PM
Thanks for all the help, Car is now sorted, Found some BMW experts trick of bleeding the System, Block Rad Bleeder and open Thermostat Bleeder and Blow into expansion tank, Tighten the Thermostat bleeder once water flows smoothly, then blow into expansion tank until water flows smoothly out of the Rad Bleeder and fill Expansion tank to correct level, Haha who would have thought it was THAT simple...

Yeah I might look further into the Engine swap, I have a full Manual conversion kit sitting in my Garage waiting for the day i decide im over the very smooth auto

Thanks again Tourburgring