Thread: L322 Coolant System explosion

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.

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

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.

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,

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

Originally Posted by 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,

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

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.

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