Water pump replaced, still leaking coolant

Mozambique

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2010 LR4 V8 with 90k miles.
So I had a v slow coolant leak for 6 months that started getting faster. Took it to my regular garage and they diagnosed the plastic pipe off the water pump was leaking. I got them to replace it and also the water pump as PM. got the car back and still leaking at same rate with coolant visible as per pics. Level in reservoir dropping by a couple of inches every 100 miles or so.
took it back to garage, However after the 30 mile drive to the garage there was no visible leakage?? they did a pressure test for a couple of hours and still no leakage. I questioned their original diagnosis and asked them if maybe plastic crossover pipes could be the problem. Could be leaking from more than one place? Was told they tend to fail catastrophically as opposed to slow leak.
I took the manifold at the front off, the one which connects to both air filters to get a better view, source of leak not clear.
Before I take it back to them again, I thought I would ask here?
Already spent $CAD 1k on water pump and pipe replacement so far.......not leaving me feeling warm and fuzzy.
Any help much appreciated!!
 

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jlglr4

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How much driving did you do after the water pump change and before taking those pics? Just wondering if you had a bunch of coolant down in the “V” of the motor from the leaking oil cooler pipe, and it just spilled out from driving it. If you’d been driving it for a while, the coolant should have evaporated on that hot block, and that much coolant would indicate a new leak.

As for the dropping reservoir level, that could be from the garage not bleeding the coolant lines completely. If you bleed by the old fashioned method rather than using a pressure/vacuum refill, it sometimes takes a while for the coolant level to stabilize.

If you do have a new leak, it can really only be the water pump or crossover pipe in that particular location. Could be they didn’t get the oil cooler pipe on the water pump in correctly when they replaced it, or maybe they re-used one of the old o-rings (sold separately from pump). Or maybe that crossover pipe is about to go and is deforming and leaking only under certain conditions.

Normally, I’d say mop it up and keep an eye on it - maybe put a UV coolant dye into the system. But
at 90K, I’d just go ahead and have the coolant crossover changed out if it hasn’t been done before. You don’t want to wait for a catastrophic failure.
 

Mozambique

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Hey, thanks for your thoughtful reply.
Done over 100 miles so defo a new leak. Yes, initially they said maybe air burping out. They used new seals, and they do good work, have used them for years. I also wondered if maybe seals got damaged when they installed the new water pump and pipe. Sounds like I should get front and rear crossover pipes done anyway. I do what work I can myself on the street, as no garage. Not sure I fancy taking inlet manifold off and potentially exposing engine internals to dust etc. if windy :(
 

Mozambique

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You mean the front crossover pipe. I should replace the rear one too I presume. Do you know the name / part # for the rear one? They are both plastic and prone to cracking right.
 

jlglr4

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Just really strange that the garage wouldn’t have found something with that much coolant splashing around.

Yes, should probably do both. Front is called outlet pipe, and rear is called heater manifold. I don’t have part numbers handy, but there are some threads on here with the complete parts lists. Just make sure you’re looking at V8 (V6 parts are different).

As for doing it on the street, just depends on your comfort level. You can protect the internals sufficiently by just shoving rags or taping over the intake ports (I use wide blue painters tape) once you have the manifold off.

With the manifold off, you can see straight down on that oil cooler pipe and double check that it’s seated correctly as well.
 

Jhgrn3

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The crossover pipe is the most common culprit. It is what that plastic tube behind the water pump connects to. Unfortunately you have to remove the plenum to access it. It leaks from the seams and from the seals. You will get a good view with the plenum up. You do not have to disconnect all the stuff on the rear of the plenum to access it. Good luck
 

Mozambique

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Thanks...... appreciate your thoughts. The plenum is the intake manifold, right? I assume it has a gasket that should be replaced?
 

Mozambique

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Well, intake manifold off and front crossover pipe removed. Coolant visible on either side more towards front so I am thinking the front crossover is the culprit. No signs of cracking in it. O ring seals at the V end look a bit flattened, so maybe leak from there. Coolant present on mating surfaces immediately around some of the inlet ports on the block...... some coolant getting sucked into engine I guess. No obvs signs of poor running, so I guess small quantities not a big problem, if a bit concerning
 

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Mozambique

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Piece of cake so far! Waiting for 1/4" torx socket to arrive so I can tackle the rear heater manifold pipe, plus need to order parts
 

jlglr4

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The coolant on the inlets is strange. I get that a leaking intake manifold gasket might have sucked it in, but I don’t see how that coolant would have gotten from the valley of the engine up to the intake port, unless it was spraying out under pressure - guess that’s possible. Might also inspect the throttle body for coolant inside or out - they run coolant around the throttle body (as I’m sure you noticed) and I’ve heard of leaks in the throttle body as well. Maybe a leak there could have dripped down around the intakes from the top.
 

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