E39 530i MS -Coolant burst out expansion tank but engine cold.

[azan23uk]

Hi All. My previous E39 528i never had this issue. Lately, when checking coolant in the morning when engine cold, my coolant always bursts out when i open the expansion tank cap. Is it normal or there is something sinister lurking? My suspicion is my head gasket has leaks and causing the engine compression to pressurise the cooling passage beyond its limits. My mech says its quite normal to have this. I have doubts. Anyone have an idea? Tq bros.

 

[moots]

Bro.....not normal.do a thorough bleed of the system again and see.if the cooling sys is still under pressure with a cold engine...you have problems....big one....i'd do a cylinder compression test.....

Sent from my GT-I9070 using Tapatalk 2

 

[azan23uk]

Bro.....not normal.do a thorough bleed of the system again and see.if the cooling sys is still under pressure with a cold engine...you have problems....big one....i'd do a cylinder compression test.....

Sent from my GT-I9070 using Tapatalk 2

I'm thinking of the same thing too. Which workshop would you recommend? Thanks Moots.

- - - Updated - - -

Bro.....not normal.do a thorough bleed of the system again and see.if the cooling sys is still under pressure with a cold engine...you have problems....big one....i'd do a cylinder compression test.....

Sent from my GT-I9070 using Tapatalk 2

I'm thinking of the same thing too. Which workshop would you recommend? Thanks Moots.

 

[bimmerholic]

Azan, if you were to bleed it properly, you'll have to turn your heater all the way to 32C so it opens up the passage to the heater core as well. Chances are there may be air still trapped in the system after all. Most mech's don't know this as they may assume most people would have done a by-pass of the auxiliary heater water pump.

 

[zidee]

Azan, if you were to bleed it properly, you'll have to turn your heater all the way to 32C so it opens up the passage to the heater core as well. Chances are there may be air still trapped in the system after all. Most mech's don't know this as they may assume most people would have done a by-pass of the auxiliary heater water pump.

Bimmerholic, what is the right way to bleed?

Engine running?
Heater turn all the way to red end?
Radiator cap removed?
Unscrew the bleed screws?

please advise

 

[bimmerholic]

Bimmerholic, what is the right way to bleed?

Engine running?
Heater turn all the way to red end?
Radiator cap removed?
Unscrew the bleed screws?

please advise

Close...you've got 2,3&4 right.

Here's how to proper bleeding: (Note: when filling up the coolant reservoir, do it slowly and steadily and calmly. Do it fast and you're gushing more air in.)

1) Suggest to do it only in the morning when engine is cold. (When car is asleep for 8hrs or so overnight)
2) Without starting the engine, turn up the heater both driver & passenger side to 32C with speed 1 or 2 bars.
3) Pop hood up and you should hear your auxiliary water pump and heater valve turned on. You know this by the slight but constant vibration on the auxiliary water pump. (it's on the left side of the front strut tower for pre-facelift and next to left side of radiator for facelift respectively).
4) Unscrew & remove coolant reservoir cap and both the bleeder screws.
5) SLOWLY fill up the the reservoir till the brim and let it overflow while constantly monitoring the amount of air bubbles purging out of the bleeder holes. Note: The bleeder hole on the thermostat housing will be the first to purge air out.
6) Once you notice there is no longer air bubbles from the bleeder hole that's on the thermostat housing, stop the filling and slowly tighten that bleeder screw back on the thermostat housing.
7) This step forward you will continue to fill and let it overflow. Continue filling until the second bleeder hole (next to reservoir) has no more bubbles. Stop the filling and screw back on this bleeder hole.
8) At this stage you would have bled 99% of air from the entire cooling system. Continue bleeding till there are no air bubbles at all from the coolant reservoir. Now you can tighten the reservoir cap back on.
9) DONE!

You'll notice your engine core temp will be lower now (if you have air previously trapped in the cooling system).

- - - Updated - - -

Bimmerholic, what is the right way to bleed?

Engine running?
Heater turn all the way to red end?
Radiator cap removed?
Unscrew the bleed screws?

please advise

Close...you've got 2,3&4 right.

Here's how to proper bleeding: (Note: when filling up the coolant reservoir, do it slowly and steadily and calmly. Do it fast and you're gushing more air in.)

1) Suggest to do it only in the morning when engine is cold. (When car is asleep for 8hrs or so overnight)
2) Without starting the engine, turn up the heater both driver & passenger side to 32C with speed 1 or 2 bars.
3) Pop hood up and you should hear your auxiliary water pump and heater valve turned on. You know this by the slight but constant vibration on the auxiliary water pump. (it's on the left side of the front strut tower for pre-facelift and next to left side of radiator for facelift respectively.
4) Unscrew & remove coolant reservoir cap and both the bleeder screws.
5) SLOWLY fill up the the reservoir till the brim and let it overflow while constantly monitoring the amount of air bubbles purging out of the bleeder holes. Note: The bleeder hole on the thermostat housing will be the first to purge air out.
6) Once you notice there is no longer air bubbles from the bleeder hole that's on the thermostat housing, stop the filling and slowly tighten that bleeder screw back on the thermostat housing.
7) This step forward you will continue to fill and let it overflow. Continue filling until the second bleeder hole (next to reservoir) has no more bubbles. Stop the filling and screw back on this bleeder hole.
8) At this stage you would have bled 99% of air from the entire cooling system. Continue bleeding till there is no air bubbles at all from the reservoir cap. Now you can tighten the reservoir cap back on.
9) DONE!

You'll notice your engine core temp will be lower now (if you have air previously trapped in the cooling system).

 

[bimmerholic]

OH yes....20cents coin will come real handy when loosening/tightening those bleeder screws. The old 20cents coin.

 

[zidee]

Good one bimmerholic. Thanks for sharing

 

[azan23uk]

Hi All,

My mechanic saw the pressure build up and pretty convinced of blown gasket. Header has been taken out as we speak. Slightly warped and one of the valve seats is broken. Thermostat is also faulty. Header is sent to skimming. He consoled me that the warping not a serious one. I put aside a top overhaul budget for q1 next year...but looks like it's gotta be pushed few months earlier. But relieved temporarily. Hope the skim job won't reveal any crack on the head. Otherwise mine will too...hah hah hah. Thanks to all bros here.

- - - Updated - - -

Hi All,

My mechanic saw the pressure build up and pretty convinced of blown gasket. Header has been taken out as we speak. Slightly warped and one of the valve seats is broken. Thermostat is also faulty. Header is sent to skimming. He consoled me that the warping not a serious one. I put aside a top overhaul budget for q1 next year...but looks like it's gotta be pushed few months earlier. But relieved temporarily. Hope the skim job won't reveal any crack on the head. Otherwise mine will too...hah hah hah. Thanks to all bros here.

 

[V-Man]

do check for any hairline crack on the warped head. if got, do consider finding a replacement instead of skimming and ensure to re-thread and get new head studs (personal experience)

had similiar problem and after skim > crack again > change head (didn't change all head stud and re-thread) > overheat again > spent thousands > finally swapped the whole engine

 

[alantiong]

new head studand rethread is a must.. no option here

 

[bimmerholic]

do check for any hairline crack on the warped head. if got, do consider finding a replacement instead of skimming and ensure to re-thread and get new head studs (personal experience)

had similiar problem and after skim > crack again > change head (didn't change all head stud and re-thread) > overheat again > spent thousands > finally swapped the whole engine

new head studand rethread is a must.. no option here

Are new head studs & rethreading a must when one carries out an overhaul on a normal running high miler engine (never overheated)?

There is an overhaul kit that mechanics use when overhauling an engine. I assume the headstuds are separate items that do not come with that kit. Correct me if i'm wrong.

Would be beneficial for all if those who have carried out an overhaul before can enlighten what are the non-common items to look into/replace/do when overhauling?

Food for thought.

 

[azan23uk]

I'd relay the tips to my mechanic. I think he's changing the bolts. Just hope the thread can withstand the torque applied when tightening. TQ

 

[harbhajan]

hai try replace the exp tank cover,i had that problem and it worked