L322 cooling system

ok just a quick question for the techies amongst us, 2003 4.4v8 RR, i did a run of about 450 miles on thursday, anyway car ran fine no issues, although monitoring coolant temp it did get to 109/110 degrees a couple of times whilst stood in traffic, anyway did the trip, parked the car up and not driven it until today, jumped in turned on the ignition and 'bong' check coolant. to cut long story short i went to undo the expansion tank cap and strangely there was quite a bit of pressure (or maybe vacuum) in the system, it was like opening the top on a bottle of fizzy pop so i guess it rules out cooling system leaks. i topped it up and it was around half a litre of water/coolant mix (if that). my only thought to the coolant loss is i have a 140 cap on the system (which is the one now listed for the 2003 l322), howver looking online i have found the water pressure at 110 degress is 1.43bar, and at 109 its just under 1.4, am i just being a bit paranoid and it's prob just bled a little coolant out to keep the pressure to 1.4?

I think there was a revised cap at 210.....

Not sure, it was a 160 cap I believe originally and it was revised to 140 to reduce cooling system pressure and reduce the risk of the expansion tank splitting

RRkev said:

Not sure, it was a 160 cap I believe originally and it was revised to 140 to reduce cooling system pressure and reduce the risk of the expansion tank splitting

Click to expand...

Ahhhh...yes, I may have it the wrong way round then!

yes looking at lr cat pre 1a chassis number is a 200 cap everything after has been revised to 140, bit crap though if the car hits 110 and bleeds a little lol

Car should run around 105-108...

it normally does run 106-108 or down to around 92 if electric part of the stat engaged, but it peaked at 109/110 3 or 4 times thurs, after cruising at 70ish then coming to a stand still in traffic, it was only for a short time and soon came back down but i guess it was just long enough to let some coolant out.

Remember, coolant is NOT water....your googling would suggest water at pressure/temperature etc....

Engine coolant is filled with various compounds that will increase the waters boiling point, reduce pressures and increase heat exchange.

I have had an L322 over heat to 134 degC and no pressure loss through the cap, hoses rock solid from the pressure, but no leaking from the cap.

I would suggest your coolant loss *maybe* from somewhere else, there are many other prime suspects on the M62/L322 before considering the cap.

yes i'm going to monitor it for a few days and see what happens, although it is holding pressure in the system as i get the pressure release when i remove the cap, but i'm not ruling out something leaking whilst hot.

Do the 80 degree mod or chuck in the standard stat like the one I have in my garage but can’t remeber the part number of, it’s 88 degrees though and a lot cheaper than what I paid now . I have a 140 cap on mine but don’t ever sit in traffic .

just to update this, i found the top rad hose seeping water last week, i've just replaced it with a genuine hose and refilled the system, however temps were still the same ticking over and now, as soon as i drive it they are hitting close to 130, i'm not fully ruling it out but i think i may have head gasket issues

If you excuse the pun, they are a bleeding pain to bleed.

My mate took mine to it's MOT and left it sitting at idle for 15 minutes and he said the temp gauge went up to to the red which it has never done. The last time i had it apart I only did a quick bleed and i think that is the problem.
There is an auxiliary pump bolted to the inner passenger wing that doesn't work either and i think that is supposed to help with bleeding.

What i found with mine after reading a site, may have been meeknet, was to raise the front of the vehicle up on a sleeper, i filled the coolant to almost the brim and burped the pipes coming and going fom the rad.
The bleed screw also allows quite a bit of coolant out during the process as does the expansion tank but i catch it in a big plastic storage container and then filter it and put it back in.

Have a look at this plus i saw several youtube clips while searching this.

https://www.meeknet.co.uk/E38/E38_Bleeding_The_Cooling_System.htm

yes i'm aware of the pump if it works it's supposed to help keep the heaters at full temp when idling, however on filling up the 'correct' way is to set heater controls to max then put the fan one one click which should circulate the coolant to the heater, however to complicate mine i have an lpg system plumbed into those pipes which is a pain to bleed it. anyhow big big sigh of relief i think i've sussed it! it turns out after posting earlier i decided to have one more go at it, temp rose again gurgling etc etc, however it caused the fault to show....it was in fact my lpg regulator it was sizzing and hissing from the water inlet/outlet so as well as leaking it was letting air into the system causing it go over temp. i've disconnected the water hoses from it for now and used a piece of copper pipe to link the pipes together. filled it back up burped the pipes bled it, then took it out for a test it did reach 112 degrees at one point but soon came down to 109/110 it's probably running hotter this time of year to allow for the colder air temps, and i notice when the air is colder the electronic side of the stat dosent kick in so much. so fingers crossed it's panic over and no head gaskets required.

The reason for the fan motor on low is to make the aux pump run to help bleed the heater matrix - if that isn't running it is a pain to bleed correctly.

I kid you not, I have spent 3 hours bleeding, burping and constantly running water from a hose into the expansion tank before to ensure I get every little air bubble out.....do not underestimate the difficulty these things take to bleed the cooling system.

well good news today, it's still running warm at 109-112 degrees however, i did think raditor could be an issue as the temp reading was in the low 20's but after the electric stat kicked in the rad temp rose so i'm pretty sure it's ok, although when draining the system yesterday i had to screw the drain pug almost right out to get it to drain so could be a crap in the bottom issue, but i'll monitor it. but the temp cam back down to the upper 30s after hitting 70 when the electric stat opened.

however besides the still running a bit warmer it hadn't lost any coolant as it had before i did the hoses etc and i got the usuall small pressure release on removing the expansion tank cap this morning not the larger whoosh i was getting before (like opening a bottle of fizzy pop). it's also not dumping coolant out of the expansion cap and the heaters are hot, where they kept going cold before.....best guess they run warmer in colder weather to accomodate the colder air intake maybe dunno. but it seems this whole problem was down to the lpg reducer leaking, and i think it was leaking lpg into the coolong system as at one point last night i smelt gas when taking off the expansion cap, and of course if gas is going one way coolant was probably going the other. anyway rang my usuall lpg guy this morning to be told he dosen't refurb reducers (which is funny as he refurbed my current one when he serviced it last year) then quoted me £180 for a reducer or £200 fitted, quick tinternet search and found the reducer refurb kit at the lpg shop for £29 delivered (a new reducer is only £94) so that's my job for possibly this weekend sorted (if i don't goto the nec classic car show) certainly £29 and a bit of my time is far cheaper than the pain of head gasket replacement.

The engine does not have a 'Cold Weather' mode - I would be checking your radiator - it could be silted up at the bottom.

The Gearbox however, does have a 'Cold Weather' mode and will hold lower gears longer to help the engine warm up faster and into economical running temperature ranges.

My news ones running well will be doing the 88 degree stat mod when it arrives, looks like iv bought a good in.

I did wonder, the rad has been on 5 years and done around 50,000 miles, as I said above I did notice I had to virtually take the drain screw out to get it to drain. Fingers crossed it’s running ok at the moment. I’m planning doing a complete cooling system overhaul after Xmas replacing all the hoses, the manifold on the transmission cooler and most likely the rad to. I have noticed it was difficult getting the system to fill, even this afternoon after all that running & bleeding I had to burb the top rad hose again as it was full of air.