I've got a d16z6 that seems to be losing coolant slowly. I only think this because the other day I looked in the engine bay and saw an empty coolant reservoir and took the rad cap off and saw it was a little low.

Now when I'm driving the car normally (shifting around 3K) I never see smoke, but occasionally I'll smell something funny. Whenever I indulge in "spirited-driving" I'll see some white/grayish smoke around/close to vtec engagement.

I've been talking to a buddy and he says it might be the head gasket, but I wasn't too sure. I'm thinking if it is the head gasket then it's just cracked and not blown because the car drives completely fine. You wouldn't notice anything out of the ordinary if you were driving normally.

Could maybe the head be warped and small amounts of coolant be leaking into the cylinders? The car has overheated before, but it was never anything too bad. Maybe the heat caused just enough damage to warp it?

 

compression test. leakdown test is better if you have access to one. there's no such thing as a cracked headgasket when you're talking about MLS. if it's blown, it's blown.

 

Ok I'll probably do a compression test later today then. Do you have any thoughts on what else it could be if compression is good?

 

leaky hose or radiator. especially if you can smell it.

you shouldn't smell coolant inside the cabin anyway if you're burning it inside the engine. assuming your exhaust doesn't leak, of course.

 

Alright thanks, I'll let you know the results of the compression test

 

So this afternoon I did the test, and the results don't seem good at all.

C1 C2 C3 C4

100psi 90psi 85psi 110psi


Now when I was cranking it, I'm not sure if there was something I did wrong or not, but the needle would jump and hit around 130 or 140 psi for the cylinders. This was only for a split second though and the needle stayed steady around the numbers listed above.

 

sounds like you need to buy a new compression tester. the needle should STAY at the highest pressure reached.
also, do a valve lash adjustment. out of spec valve lash will have a pretty big effect on compression test numbers.
and when you do the compression test, you should be removing the ecu/efi fuses so it disables the ecu which will disable spark and fuel, and you should be holding the gas pedal to the floor as you crank it over. and you should be cranking it over until the guage stops rising.

also, while doing the compression test, take the radiator cap off and make sure the coolant is topped off. and have someone watch the coolant in the radiator as you crank it over each time. if the coolant stays steady, it's a good sign. if the coolant starts to rise, or actually jumps up and down each time the cyl is on the compression stroke, then the HG is probably leaking in that cyl that is being tested

and if you're able to do a leakdown test, remove the rad cap for that too. that's actually the better way to test for HG leaks. when you pressurize the cylinder, if the HG is leaking you'll definitely see the coolant level start to rise or even start bubbling.

 

it could be a leaking heater core if your new compression tester (they're $20 at most parts stores and harbor freight) tests fine and no other visible leaks around the engine bay

 

Okay thanks motoxxxman I'll buy a new tester and be sure to do what you said. And holmesnmanny I'll check out that heater core to see if that could be it. I'll retest sometime this weekend and I'll post whatever results I get