L322 Coolant System explosion

[danske]

Hi , just returned home and parked the 2003 Vogue and it had a massive explosion under the hood and the coolant started to gush out , including the rusty water.

Having just had pipe replaced last week ( due to Rats eating holes in the T section ) im a little concerned as to how this has happened ?

Is there any suggestions / experiences as to why this might have happened ie Not being bled properly , poor application of hose pipe and clamps etc. Im awaiting our Mechanics inspection ,however am trying to understand if there are any issues in general other than quality of workmanship in replacement of hose pipe last week.

thanks

[danske]

further info on the issue , it appears the Header tank under the front passenger side guard has blown apart ?????? The pressure valve should have released , but the mechanics are not sure.

[RangieBit]

Yep, the pressure valve should have released but typically it relies upon hydraulic pressure to release the valve. That is, the coolant needs to expand enough to place pressure on the relief valve in the header tank cap. This may not trigger under air/steam pressure alone.

If too much air was present in the system when it was sealed then pressure could increase significantly enough to break parts of the system with out the relief valve being triggered properly.

I have seen similar things happen on other marques where the air bleed process was not followed correctly at the time of coolant replacement. Not suggesting that proper procedure was not followed in your case (though it is a possibility) just that similar explosive incidents have been known to occur.

Addendum: Just checked RAVE and it is very particular about the air being bled from the system while and after engine reaches operating temperature. Doesn't mention the potential outcome of incorrect air bleeding but I think we know what happens.

Hope this helps.

Cheers,
Iain

[danske]

Cheer Iain, thats very helpful , It does seem a little co incidental that the coolant system was bled last week and this now happens! I dont want to accuse these guys of noit following correct procedure without having full facts and possibilites , at this point though after driving it all over Melbourne and back home to Gippsland over the weekend , it seems strange that this would happen now.

Do you happen to have the correct bleeding procedure out of workshop manual by any chance, or know where to get it ?

Further to this , I would have thought if the system was fully bled why would old rusty water be evident in the coolant when it came out ? It should not have been there in the first place , but it was a different colour to the red coolant.

Mechanic stated that they dont always bleed them fully depending on where the bleeding takes place from ( ie if halfway up the height of the engine then it would only be half bled ) so this may be a factor in the inccorrect procedure theory.

[stig0000]

is it a v8,,, if it is i woudlent put it past it that a pipe or header has blown,, they run a big press in the cooling,

[RangieBit]

Hey again Danske,

Can't speak for your friendly neighbourhood repair folk. I always replace all the coolant as it's an unknown factor when I need to replace something in the cooling system (like a hose for example).

The following procedures, Drain and Refill, are as per RAVE.

Drain
1. Position vehicle on lift
2. Set heater controls to maximum.
3. Disconnect battery earth lead.
4. Remove engine access cover.
5. Position container to collect coolant.
6. Remove coolant expansion tank cap.
7. Fit tube to drain tap.
8. Open drain tap and collect coolant.
9. Remove cylinder block drain plug. Discard sealing washer.
10. Collect coolant.

Refill
1. Clean cylinder block mating face and drain plug.
2. Using a new mating washer, fit cylinder block drain plug and tighten to 25Nm (18lbf.ft.).
3. Close radiator drain plug and remove tube.
4. Cover alternator to prevent fluid contamination.
CAUTION: Care must be taken to ensure that oil or fluid does not enter or contaminate the alternator
5. Remove bleed screw from expansion tank.
6. Remove coolant bleed screws from coolant rail and EGR cooler.
7. Fill cooling system.
8. Close bleed screws to coolant rail and EGR cooler when a constant stream of coolant is emitted.
9. Remove cover from alternator.
10. Connect battery earth lead.
11. Connect exhaust extractor to tail pipes.
12. Start engine, bleed air from cooling system and allow engine to reach operating temperature.
13. Fit and close expansion tank bleed screw when a constant flow of coolant is emitted.
14. Visually check engine and cooling system for signs of coolant leaks.
15. Disconnect battery earth lead.
16. Wipe coolant from chassis and surrounding area.
17. Fit engine access cover.
18. Top up cooling system.
19. Connect battery earth lead.

I think they are suggesting that steps 15-17 take long enough that the system has cooled sufficiently. Topping up the coolant should only be done when the system is not at full operating temperature. The top up procedure is in the owners manual. I think there is a graphic on the expansion tank also about the float position for reference as well.

Hope this is of use to you.

Cheers,
Iain

[danske]

is it a v8,,, if it is i woudlent put it past it that a pipe or header has blown,, they run a big press in the cooling,

yes a V8 , can you explain what you mean by a "big press in the cooling"

[danske]

This a very thorough response. I will certainly raise this with them and understand if they did follow this procedure. I wil report back for interest sake as to the outcome of the situation. They are replacing header tank tomorrow and are testing for the cause of the issue. something about checking if the head gasket has a leak and there fore air is getting in that way ???? could be speak for , dont have a clue , so we will go for that as a response. :confused:

[RangieBit]

Hmmm,

Well it is certainly a possibility. Although a head gasket that lets air into the system (typically while engine cooling) just as readily weeps that same air and coolant back out again as the system comes under pressure. There are usually signs which your mechanic may have missed since they were repairing a hose not checking for this.

A cracked head would consume water and potentially aerate the system but this too has other external symptoms. Again, this would not be something you'd actively look for under the circumstances.

Like the old maxim - If you hear hoof beats, don't think zebras.

Your description of a mixture of rusted and pinkish fluid is a little concerning as this tends to suggest a blockage somewhere. If the coolant is circulating properly around the system it should have the same level of contamination. That is, be equally off colour than new coolant. The presence of rust in only part of it suggests that the fluid has been trapped somewhere and the rust inhibitors have been all used up while it's been trapped or its just been in there too long.

Of course a similar outcome can have occurred if you had a vapour lock and the old coolant (which they may have left in if they only partially drained the system) didn't mix with the new coolant they used to top it up again after the repair. This is one of the things that can happen if you don't drain and bleed the system properly and end up with air in the main engine/radiator cooling system.

Modern cooling systems are effectively closed systems and pressurised to a high degree. They shouldn't ever need topping up unless your vehicle has been VERY hot for extended periods. This excess heat will cause fluids to be lost by release from the relief in the expansion tank cap. Typically it doesn't tend to be a major event either, more like a slow weep each time. This is why despite the seal they recommend checking it at least weekly.

Older systems were not sealed in the same way and expelled fluids fairly readily when the coolant expanded to such an extent that it went beyond the capacity of the expansion tank. You'll see this by the relief usually being in the radiator cap, and not often also in the cap on the expansion tank, in these systems.

Even older systems didn't even have the expansion tank and we all know what happens in those systems when they get too hot. Your car resembles the 1950 midnight flyer. Lots of steam!

So there you have it. Your Cooling System and You 101.

Cheers,
Iain

[danske]

So it was the header tank that blew up. Apparrently something to do with an incorrectly rated pressure release valve on the cooling system. According to our mechanic and their supplier who advises them ( ritter ) the one on my car had 200 written on it and the correct one should be 140. I assume this is PSI. they felt that they followed corrrect procedure in bleeding , but have agreed to pay for the tank replacement.

Anyway hoepfully this is solved and that the only issue is the vlasve and therefore , not more coolant issues.

thanks for information.

[gunnarL322]

.
.
12. Start engine, bleed air from cooling system and allow engine to reach operating temperature.
13. Fit and close expansion tank bleed screw when a constant flow of coolant is emitted.
14. Visually check engine and cooling system for signs of coolant leaks.
15. Disconnect battery earth lead.
16. Wipe coolant from chassis and surrounding area.
17. Fit engine access cover.
18. Top up cooling system.
19. Connect battery earth lead.

I think they are suggesting that steps 15-17 take long enough that the system has cooled sufficiently. Topping up the coolant should only be done when the system is not at full operating temperature. The top up procedure is in the owners manual. I think there is a graphic on the expansion tank also about the float position for reference as well.

Hope this is of use to you.

Cheers,
Iain

Hello Iain, I drive a L322 on the other side of the globe (Sweden) but the other day I came to grips with a problem I had with radiator hose overpressure.
My expansion tank cap was faulty, and in a one-way-valve fashion allowed air to be sucked in when the engine cools down (some vacuum occurs when the fluid contracts). Then upon engine warmup the fluid and trapped air combined would cause over pressure. The new cap (same 140 rating) does not allow air to be sucked in and I notice when the engine cools down it even sucks the radiator hose a bit flat from vacuum. This seems a good thing because when the fluid expands the flattened hose will take up fluid volume as it expands and finally at full operating temp the hose pressure seem quite normal.

So connecting to what you said, if I would open up the cap with cold engine to do some topping up I will lose that vacuum. Then upon warmup I assume the pressure will build up now going from neutral/no pressure up to a bit higher than if I began from vacuum. I assume this would mean the cap hopefully reach a limit to release any overpressure?, thus can I assume the cap pressure limit actually works to calibrate the hose pressure ? Otherwise at what temp "halfway" that would be suitable to do the topping up at seems a vague thing. In my homebrew way I would rather monitor the pressure buildup and unscrew the cap a bit to let some subjective excessive pressure out at the cap at full temp until hose stifffness feels good to my taste.. Then upon subsequent cooling down the system will again go into a vacuum state sucking the radiator hose a bit flat. :)
Well I am not sure about how that cap pressure release works. Anyway the behavior I am getting now looks good to me. The top hose of the radiator goes from sucked a bit flat when cold up to some decent pressure at normal temp and I am pleased so far the way this works. At least when I return to the car the next morning and find the hose still in vacuum state at least it tells me I have no air leaks. :angel:

[RangieBit]

Hi there Gunnar,

I don't profess to be an expert in these things (in fact far from it!) though one thing does occur to me.

According to the recommended coolant replacement procedure which you have quoted, the cleanup/top up step is done after the engine has been to normal operating temperature so that the thermostat is open and the fluid was freely circulating through all of the cooling system. This so that any air, if present, will be in the top part of the system.

I don't know if your shrunken hose is normal or abnormal as the climate here does not get truly cold to the extent that you would normally experience.

I'm also willing to defer to other owners in the northern hemisphere here but even in -10deg C alpine conditions in Australia I've never seen a partially collapsed top hose in a properly functioning system. So if anyone out there in a truly cold climate can confirm if this normally happens I'd appreciate also. Anyone out there in northern Canada perhaps?

If your service centre checked the coolant level when they replaced the cap to ensure it was OK then I'd be inclined to think this may be normal in your very cold climate.

At worst here it's not a complicated task to check the coolant level as per the owners manual although I probably wouldn't do it first thing in the morning. Perhaps, if possible, an hour or so after the engine has been run to normal operating temperature and then cooled down, so that the coolant is less likely to be under any pressure and not yet truly ambient temperature cold.

As a base line, if the system seems to be operating normally now then your shrunken hose when the system is cold (as in first thing in the morning cold) may also be entirely normal.

Hope this helps some.

Cheers,
Iain

[gunnarL322]

Hello my earlier post on 140 cap and sucking hoses flat is not a good solution.
I finally ended up discovering that the cap I had replaced had a 200 pressure rating. And when I reinstalled that one my problems disappeared, part from that running with high pressure water hoses is kind of setting life up for excitement.
I will bring this up with an authorized service centre and hear what they have to say about why certain series require the 200 cap.

[p38arover]

A cross post from another thread:


I've noticed that my car's coolant level keeps dropping. I hadn't found any obvious source of leaks until last Saturday.

My coolant expansion tank is leaking down the RH rear corner - there is a tell-tale white streak which, after being cleaned off, returns after the next run.

Looking at the Full Fat RR forum to see if leaking tanks are common, the general consensus is that the BMW M62 4.4 V8 cooling system should have a 200kPa cap, obviously to allow a higher pressure and thus higher operating temps.

Perhaps this is the reason for coolant leaks. I'll replace the expansion tank but I'll leave the 140kPa cap in place for the moment.

My L322 runs at 99-100 deg C on the motorway but soon rises to 103 deg C in traffic (temps according to both ScanGauge and the L322 Message Centre).

Edit: I just had a look at MicroCat and found the cap specified is:
Up to VIN (V)1A001049, it is PCD100200L (which is probably the 200kPa cap)
From VIN (V)1A001050, it is PCD100070 which is the 140kPa cap.

My car's VIN is 34A145nnn so I don't know why it had a 200kPa cap.