Mk3

ChrismonDA

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May 2, 2004
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NC Johnston Co
Ugh. It's not overheating and I am not smelling any coolant, This has been a very reliable truck fingers crossed I will do a pressure test.
 

1MITCH1

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Jan 24, 2007
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Daphne,AL
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HR2

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Common sources of coolant leaks maybe they are small enough not to show or smell.
Plus being a BMW engine it uses that Blue coolant that smells different from the usual stuff.
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
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Los Angeles, Ca
I highly doubt its the head gasket. Have you pressure tested it? Coolant is probably leaking from the radiator, one of the hoses (especially the small coupler in the back), or the expansion tank is cracked. Another likely scenario is the "swimming pool" under the intake is leaking, which drains into the bell housing.
 

discostew

Well-known member
Sep 14, 2010
7,735
1,026
Northern Illinois
I highly doubt its the head gasket. Have you pressure tested it? Coolant is probably leaking from the radiator, one of the hoses (especially the small coupler in the back), or the expansion tank is cracked. Another likely scenario is the "swimming pool" under the intake is leaking, which drains into the bell housing.

x2
 

jymmiejamz

Well-known member
Dec 5, 2004
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Los Angeles, Ca
Another less likely scenario is the plate on the back of the motor behind the flywheel is leaking. I've never had to replace one, but you would have to pull the tranny to do it. Pull the rubber cap on the bottom of the bell housing and see if there is coolant in it.
 

ChrismonDA

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May 2, 2004
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NC Johnston Co
Did a pressure test could not find any leaks and held pressure. But I will do another pressure test it could be a small pin hole because I only have to add a liter of fluid once every other month.
 

bri

Well-known member
Apr 20, 2004
6,184
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US
If you had a leaking heater core on an MK3, where would the coolant go?
 

bri

Well-known member
Apr 20, 2004
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155
US
I have. But it was RRC/P38 it you never have a passenger and get in the passenger side, it may go unnoticed for some time. Kind of wondered if MK3 might have similar problem if leaking. You may not find it without looking under mats. By the time you smell it or it leaks through pads its about to blow.
 

bri

Well-known member
Apr 20, 2004
6,184
155
US
Also I had a cracked cylinder liner for years(prior owner expected this). 4.2 RRC LWB. It used small amounts of coolant. Just kept it full. One day it drank a lot of fluid and temps rose, so I shut her down. Went back next day to get it. Filled it up with coolant. Not expecting good results. But everything seems completely normal so I drove 75 miles home no issue, started the engine swap the next day. We confirmed crack when doing the swap.
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
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Los Angeles, Ca
I have. But it was RRC/P38 it you never have a passenger and get in the passenger side, it may go unnoticed for some time. Kind of wondered if MK3 might have similar problem if leaking. You may not find it without looking under mats. By the time you smell it or it leaks through pads its about to blow.

I've seen tons of heater cores fail in RRC's and P38's, just never on an L322 RR.
 

ChrismonDA

Well-known member
May 2, 2004
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NC Johnston Co
No heater core issues. I saw on a BMW website that the coolant sensor is very sensitive. No leaks that could be seen from the radiator. Did the pressure test let it sit for over 30 minutes. Nada I even took the engine cover off and saw no leaks or even smelled coolant. I really do appreciate all of the posts of why it may be using coolant. But this is a mystery.