When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Just started freshly rebuilt L36. First start/break-in was interrupted after 10 minutes because I had a leaking fuel bowl. Fixed that overnight and started again today. Set rpm at 2500. Ran fine for 10 minutes then I noticed some knocking so I shut it down. Dieseled for a stroke or two after I turned off ignition. Pulled LH valve cover and sure enough see signs of coolant in oil.
Best case scenario would be a bad gasket. Worst case a crack in a head or the block. I have come across 2 SBC blocks that had heavy rust in the cooling chambers that eventually ate a pin hole into the cylinder.
I know none of this is what you're wanting to hear, but I've been there too.
Pull the plugs first to see if you can narrow it down. If all plugs are wet, start at the top and work your way down.
Greg
Are you sure it's coolant or just moisture. Getting it hot last nite then letting it cool and another heat cycle this morning you may just be seeing condensation.
If you get lucky and only one or two neighboring plugs are wet, pull that head, inspect the gasket for a failure and take the head to a machine shop for a pressure test to make sure it isn't cracked somewhere. It's a cheap and quick test.
Greg
However, I also noticed that the #1 exhaust valve lash was not set and that rocker arm was too loose, so that exhaust valve was probably not opening. What would that do?
Could also be the intake manifold is not sealed good. Since you have an L36, the intake is cast iron and may have corrosion pitting around the coolant passages, same with the heads being cast iron. After 50 some years, who knows if the angles are correct on all of the head and intake mating surfaces. I am not a big fan of using RTV on engines in certain locations, but I do like to use it on the intake to head surfaces and on the china wall at front and rear. It always helps everyone to see a picture of the moisture you are seeing in the oil!!
That rocker needs to be addressed but it would not have anything to do with a coolant leak.
If your plugs are all dry I would start by pulling the intake manifold and looking for any evidence of leaking around the coolant ports into the valley.
If nothing shows there then pull the heads, check the gaskets for failure and have both heads pressure tested.
If the heads check out OK then you have to look at the block. I was able to borrow a tool from my local machine shop at this point, to test the block in the car before pulling the short block and dismantling it.
This was a rubber backed plate that bolted onto the cylinder head surface, sealing the coolant ports. Another piece bolted to the water pump inlet and had an air coupler. I pressured up the passenger side of block to about 60 psi and it held fine. When I transferred to the driver's side and pressured up, I heard air down below right away. Pulled the pan and found a small corrosion hole below the piston skirt. It was about the size of a pencil lead. Engine had to come out then and get a sleeve. But that was much better than finding a crack in the block.
Cheers, Greg
If the plugs are dry i think I would dump the oil first to confirm coolant in the oil. There is always taste test to see if it is coolant. It should taste sweet if it’s anti freeze . Just a dab on your finger.
OK, thanks. Never heard of the taste test. I'm starting to wonder if I'm imaging things. Here are some pics of the head oil that seems to me to look watery, and the insides of the valve cover, which seems to show water beads.
If the plugs are dry and there IS water in the oil, that rules out a head gasket right? But it doesn't rule out an intake gasket or a crack.
You mentioned that the #1 exhaust valve lash was not set, and the rocker was loose. You might want to check and confirm that nothing is going wrong with the lifter, or cam lobe there. With your interrupted cam break in, you might be having a lifter/cam issue. This would not cause the water in the oil issue, but it is something you should check to make sure you do not have an issue there as well.
.....that rules out a head gasket right? But it doesn't rule out an intake gasket or a crack.
That rules out a leak between the coolant passage and the combustion chamber.
In the pic you, posted the oil does look a little milky. Does the dipstick show the same?
If the engine has not run for a couple of hours and you pull the drain plug, any water in the crank case will settle to the bottom and come out first. This will be very easy to spot.
If you want to be sure, do this before you take anything else apart.
DO NOT take anything apart until you narrow down where the failure is. You can defect a failed head gasket, crack, etc with external tests. If you are not familiar with leakdown, coolant fluid tests, you really need someone to help you. You can borrow a leak down tester from an auto parts store. You can test coolant for oil contamination. But it’s a little involved if you have never done it.
just curious, did you have hardened exhaust valve seats installed?
Thanks. I know how to do the compression test and leakdown test, but not the coolant fluid test. That said, I'm fairly confident I have coolant in the oil and not the other way around. So you recommend that I do the leakdown test prior to pulling the intake manifold, even though all the plugs were dry?
What all was done to the engine?? Block bored, MT wall thickness tested, pressure checked, deck cut, etc.?? Heads valve job, hardened seats in intake and exhaust??
Just asking!!
If you have access to a camera small enough to stick in the distributor hole you can check the intake for leaks. Borrow a radiator pump from an auto parts store pump the pressure up to 20 lbs or so and put the camera in the hole and look for leaks. Hopefully it's only an intake leak. Get the water out as soon as you can.
06-27-2020, 05:08 PM
66 427 L36 -- Coolant in oil on break-in
