So. I had the motor rebuilt 2 months ago. I've been chasing a coolant leak ever since. The shop is convinced it's the motor, which is warrantied. but the labor is not (different story, not important). Let me know what you all think.

Looses an inch from the expansion tank for every hour of driving
No coolant on the driveway
Slight coolant smell during driving
No CEL
Compression test is good on all 8
Cylinders 1,2,6 and 8 are brand new shiny, others have slight carbon build up.

would I smell coolant in the engine bay if it was burning up internally? would a compression test come out ok if the block, sleeve or headgasket had failed? and why no CEL? any other reason why the 4 pistons could be so clean?

 

You should be smelling the coolant from the exhaust pipe.
A compression test/leak down test will confirm what is going on and where.

 

so if the compression test was good. and I'm not smelling coolant in the exhaust while it's idling. there's a faint smell under the hood after driving.

what does the discoloration of the 2 front and 2 rear piston/cylinders mean?

 

I would say if you smell it driving and don't smell it in the exhuast when you start it or after driving that it's a leak under the hood. Maybe even the heater core in the dash is leaking. If you can't find a leak under the hood check your a/c drain for coolant. It may be draining coolant with the a/c run off water. Turn on your heater and see if you smell it in the vents. Check your radiator for leaks since most of it is hidden... You should do a pressure check on the cooling system. Pump it up to 20psi and let it sit an hour. Shouldn't drop any for the most part. If it drops start looking for the leak.

 

Are you sure your cyl numbers are right? Pass side of engine from front to back is 2-4-6-8 and driver side front to back is 1-3-5-7

 

it's been pressure tested several times with no luck.

Haven't been using AC at all lately. when it first started leaking coolant I checked the AC condensation puddles for coolant smell and didn't notice any. The heater doesn't seem to be leaking, no smell and no moisture under dash.

And yes it's 1,2,6,8. Which is apparently where the coolant enters and exits the water jacket? hence the shops conclusion that it may be a cracked block or several sleeves. But it is a newly rebuilt engine, new sleeves, newly machined block etc.

I received the whole engine as an assembled long block.

 

You said you already did a pressure test on the cooling system and it was good?

If you had an under-hood leak, it wouldn't be uncommon to smell coolant for a month or so after the leak was stopped. Did you try bleeding the system again? The shop might not have done it correctly to begin with. If not, it will appear to have a leak as it self bleeds some of the air that was in the system. Two months would seem to be too long for it to just be trapped air, but with the new engine there could have been a lot of air and it could depend on how much it has been driven.

Check the common leak areas, and bleed the system using the proper procedure. Good luck.

 

it was bled and filled under vacuum at the shop, several times now. The engine has about 2000 miles on it, and i am topping it off regularly with a significant amount of coolant.

I guess my main question is, does discoloration of the combustion chambers necessarily indicate an internal leak?

 

Just talked with DiscoMike. We came to the conclusion it must be the engine.

Huge thanks to Mike. He has always been very helpful and willing to help the LR/Disco community.

 

I've heard that sometimes after HG leaks, the pistons are spotless due to constantly being "cleaned" with coolant.