... I'm wondering if a leakdown test is the definitive test to check for any problems that occurred with my repair? There was basically zero leakage across all cylinders (I even moved the piston a bit to open the valves and ensure the gauge was working properly). I also did a compression test and got 170-180 across all cylinders. Car is a 1994 Civic RTSi, DOHC ZC. But since I'm such an amateur hack - and this being my first HG job - I want to know if there's some sort of other test that I don't know about that I should also be doing. "Oh you didn't do the booglethrap test to check for jergumshtups, that's why you screwed your engine." ****. Me.

Reason being, the blown headgasket problem was putting oil in the coolant (pressurizing the coolant system). I want to make sure that any oil I see right now is JUST residual, and not due to me being a 'tard and not knowing wtf I'm doing. I cleared out a lot of snot with plenty of rad flush, but there's bound to be leftovers. I don't smell anything funny, and the car runs great and at temp. Thanks.

 

I'm sure yer good. There isn't another test that I'm aware of except the block test but if your collant system isn't over pressurizing, it's highly unlikely you will find combustion gasses coming from the cooling system (block test).

I would clean out the oil every time you see it and after about a week, you shouldn't see any more. If your reservoir gets over full.... Then worry.

 

Sounds like a case of imposter syndrome

 

Leak down only shows cylinder sealing (or not sealing).

You can also compression check the cooling system to see if it is holding pressure (or not). Since you had a milkshake before the gasket change, this might be a good thing to look at.

 

At this juncture, what more would you possibly do other than just monitor for accumulation of oil in the coolant?

 

And this gets to the heart of my question: Since I don't know what I don't know, I defer to the wisdom and expertise of others to advise me to conduct some other test to confirm the success (or not) of the repair. I certainly don't want to continue driving if it didn't take, and get stranded or do damage to the engine. I'm trying to figure out if I can rest easy finally.

Would a coolant pressure test tell me anything more about head gasket leaks that a leak down test wouldn't?

I also ran the engine for a bit with the rad cap off: no bubbles.

 

Probably not based on the excellent compression test results. You may have a very small leak but you won't know until you drive the car for awhile and regularly monitor the coolant for oil accumulation.

 

I'd just wipe the residual and monitor.

 

HG seals the cylinders, coolant passages and oil passages. You can have a leak between any two of those, or all three.

Leak down only shows the cylinders are sealed (valves, piston rings and HG). What about between the coolant and oil passages? Coolant system pressure test CAN show if this is sealed (as long as the rest of the coolant system is sealed 100%).

If your head AND block wasn't resurfaced before the repair, you can have a leak still (minimal now, but will get worse).

You want piece of mind, test the coolant pressure and fix any leaks you get. You should be able to leave pressure in there for days, seeing minimal change (or none). 1-2 psi up or down based on outside temperature.

 

All the coolant system is under pressure (besides the overflow). If there is a leak between the coolant and oil RETURN passages from the head, you won't get oil in the coolant, you will see a loss of coolant though. No, you won't necessarily see the coolant in the oil. As the oil heats up, water evaporates out. The vapor is then disposed by the PCV system into the intake.

 

Your comments fail to address the OP's concern about SEEING oil in the coolant. The oil is likely just residual from the previous blown HG but it nevertheless concerns the OP.

 

I am suspecting a problem. I purchased a coolant pressure tester following @jdblock's post to check my results, as something seemed fishy still.

I am losing pressure. There are no external leaks, that I can find, at least. My coolant level goes down, so, it's going somewhere. I put my ear up against the oil filler hole in the valve cover and I hear what distinctly sounds like a trickling noise, that I don't think is my imagination. Still nothing discoloured on the dipstick. Stared down the spark plug holes and nothing wet on the cylinders. Still, I'm reluctant to start the car now. I'm going to drain the oil and check if I find anything.

Suggestions?

 

I guess theres nothing discolored because the engine hasn't mixed it. Have you check inside your car? Maybe the heater coil is leaking

 

How much coolant was lost? Was it lost by leaking or was there air trapped in the cooling system? Consider all of the possibilities before jumping to one of many possible conclusions.

Proceed carefully, slowly, and methodically.

 

Did your tester come with directions? There are a few tests you can do. One for HG failure, one for coolant leaks, the last test is for the radiator cap.

A leak down MIGHT not show a leak into the coolant system, far shot, but is possible. A small leak can seal with minimal cylinder pressure.

Make sure the cap is doing its job, allowing coolant in to and out of the overflow bottle.

All else fails. Drain the oil, install the drain plug and keep testing for coolant loss, make sure the radiator is full every time you test it. My idea is that coolant needs to be above the level of the HG for it to leak past the HG. After a few tests pull the oil drain plug and see if water comes out. No water? Pull the spark plugs and crank the engine. Does water come out of spark plug hole(s)?

 

He asked for other tests, not why he was seeing oil in the coolant. So. no, I didn't address it.

 

But why was he asking for other tests? Just for the fun of it? Look deeper.

 

Thanks for the input. The oil that I drained looks perfect. Dark, and no hint of contaminants by anything milky.

I drained and flushed the coolant, including out of the block. Confusingly, it looks fine. A bit cloudy, yes, but in my container there aren't even any floaty bits of oil, like I expected. That said, there was definitely milky gross oily goo at the top of the rad, a bit in the overflow, and some lining the rad hoses. I flushed out what I found.

The loss of pressure could also be due to a shitty made-in-China tool if it makes a lousy seal at the top of the rad.

I'm going to fill it up with water and try again with the pressure tester, and follow jdblock's suggestions. (Which are methodical, as Ron also suggests.) Thanks so much.

Inside of the car is bone dry, so doesn't seem to be a heater core issue.

 

One could interpret everything you posted as expected from the original blown head gasket and residual oil from it. Don't overreact until dictated by evidence.

At this point, you have no hard evidence for a problem. Just monitor.

 

Gotcha. I'm having trouble believing there would be that much oil leftover in the system from the HG failure. Especially after I flushed it through a LOT, ran two containers of rad flush through it, and drained and filled with water once, before filling it with coolant. These are the facts that make me go "hmmm", and wonder if there's more going on. This is what is dictating my current reaction.

I agree though that there's so much that seems fine (compression, leak down, engine temp, behaviour at the overflow bottle seems normal), that it's also possible that the repair is also fine. I'll expect the residual oil amounts to drop going forward, after I do a few fills over the coming days. If it doesn't, then .... cross that bridge later.

 

He already had an idea that the oil was either residual, or a current leak.

He clearly asked for other tests.

sorry, i had a college level of reading comprehension when I was in 5th grade. i didn't miss anything in this post, or feel a need to "look deeper"

 

It would be silly not be worried about every potential sign of HG failure after replacing it. I would do the same. But it would also be easy to overreact to everything knowing all the ways a HG install could go wrong.

If the cooling system were completely coated in oil, how effective would rad flush be at removing it? What's the main active ingredient of rad flush? Post a link to the product.

 

Congratulations!

You deserve a LIKE for that one.

 

YOu are only showing your true colors. later.

 

Honestly, please don't leave. I know you're both knowledgeable and trying to be helpful.