WG 2.7CRD cooling system bleed procedure - AUSJEEPOFFROAD.COM Jeep News Australia and New Zealand

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Old 23-03-2019
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Default WG 2.7CRD cooling system bleed procedure

The water temp on my WG never really got beyond 55' in any driving conditions (UK temperatures). Heater worked but wasn't great. Research suggeted a knackered thermostat so I got a new one (Behr).

Not knowing how long the old coolant had been in (or indeed what was in) I decided to do a flush using Wynn's Radiator Flush.

First problem was geting the radiator/steering shield off (only two snapped bolts). Once off I looked for the draincock as mentioned in the manual. No draincock so I pulled the bottom hose off to drain.

I chucked the Wynns radiator flush in & refilled with distilled water. Left it running for 20 mins & drained it again. Ran a hose through the header tank & the top hose into the radiator. I changed the stat & refilled with distilled water for another flush run.

I've been struggling to get the air out of the system. The (WG) manual makes no mention of the bleed valve on top of the radiator. I filled the header tank up to the line several times & squeezed the top hose to burp the system. The low coolant light comes on even when there's plenty of coolant in the expansion tank. No bubbles have been coming out of the bleed tap but the expansion tank is like kids bathtime with lots of foam coming out. Presumably this is left over from the radiator flushing additive.

The good news is that the temp gauge is now getting up to 70' (the midway mark between 40' & 100') - is this the normal position? The heater isn't putting any heat out at all so I guess that's where the airlock is. I'm not sure how to do a heater matrix flush as I can't identify the inlet & outlet pipes. All the pictorial guides/videos are for the V8 models.

I'm about to drop the coolant again for a proper fill of mixed coolant so I'd like to backflush the heater first if anyone cant point me in the right direction.

On bleeding the system, do you leave the bleed tap open while running the engine?
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Old 24-03-2019
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Ok, think I'm sorted.

Dropped the coolant (distilled water) & it was still a bit dirty so I stuck a hose in the expansion tank & left it running for 5 - 10 mins. Reconnected the bottom hose & put in 5 litres of mixed coolant. Since there was bound to be some water left in the system (probably the heater matrix I put in a litre of neat coolant then another couple of litres of mixed.

I fired up the engine with the expansion tank cap on & the bleed tap open. At least I think it was open - I've had it this way & that so many times I've lost track which way it was originally. I let it run for 20 mins (with the heater on 'Hi') then let it cool.

The tank level dropped to the min position so topped up with mixed coolant & started the engine again. By now the heater was putting out the kind of heat you would expect from a vehicle that could be operating in a cold US state in winter.

I still don't know if opening the bleed tap made any difference. The coolant system in my R129 SL is self-bleeding without the need for a bleed tap so why the WG has to have one gawd knows. I think the heat/cool cycle may be enough (and patience).
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Old 24-03-2019
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I've never had any problems just filling the radiator through the bleed port initially then topping up the overflow bottle. The way it's all plumber seems to reduce/eliminate any problems with refilling.

The thermostat is 90 degrees so it should be sitting around the 90 mark if everything is healthy. Not sure why you're seeing 70, although it's much better than 50.

Jason
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Old 26-03-2019
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Quote:
Originally Posted by bodgie View Post
I've never had any problems just filling the radiator through the bleed port initially then topping up the overflow bottle.
Through the bleed port? I wasn't aware you could do that. The port tap just seems to have two positions; across the engine bay parallel to the radiatior which is closed & fore 'n' aft 90' to the radiator which is open. The tap doesn't seem to want to pull out. The bleed port on the V8's is different to the diesels.

As far as temps go, I think it's there now;

Before (as hot as it ever got):



Now (after a short run):
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Old 26-03-2019
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You can pop the bleed port out and fill from there. The after temp looks pretty good to me, it's at 90 or so degrees, right where it should be.

Jason
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Old 26-03-2019
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Thanks for that tip. I'll remember it for next time.

You live & learn
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