SonicC

I have a civic with 182k miles I bought recently.
98 Civic EX
D16y8

I noticed bubbles in coolant when I give it some gas. After driving around for a while it will eventually lose most of the coolant due to it coming out from the radiator cap or expansion tank. There's no white smoke, hesitation, or coolant/milky stuff in oil.

Tonight I did a compression test and got the following
C1: 115
C2: 120
C3: 121
C4: 120

I also did a wet test and numbers were pretty close, with C1 being 120 this time and others remained almost the same.

I'm a little confused...I expected to see low compression on one cylinder, but this is low across the board...yet it doesn't smoke or hesitate.

Am I looking at a bad headgasket or possibly bad piston rings? At the same time, I don't think bad piston rings would cause coolant to bubble?

Jimi Hondrix

Rent (free) a block tester kit, purchase testing fluid ($10) and watch vids how to use tester.

eghatch9295

iTrader: (1)

that is very low compression on all 4.

SonicC

I guess it doesn't hurt to confirm.

Any idea what the compression is for a healthy D16y8? I figure it should be around 180?

joey1320

I think you have two issues, one a cooling system one and then the low compression.

If I was you, I would rent a pressure tester and see where the coolant is going. But you may have a simple issue with the radiator cap not holding pressure, so I would maybe replace that first.

As far as the low compression, please perform a cold and hot compression test and then a cold and hot leakdown test.

Good luck!

SonicC

The radiator cap can't hold the pressure because coolant level rises up when I rev up the engine.

I'm going to try the block tester tonight or tomorrow and if that turns yellow I'll just order new gaskets and get to work.

joey1320

When reving the engine, do you have the radiator cap on or off the radiator?

The cap should hold up to 16psi(or so), but if you have a faulty cap it can cause the same issues you're describing with the cooling system.

SonicC

I remove the cap when I rev and I can see coolant level rise up and start overflowing if I keep the revs up.

If I rev with cap on, it doesn't really leak. But if I take it for a drive, I"ll see that it has leaked around the cap.

SonicC

Also, to add: I did a warm compression test this morning...let the engine get to normal temp and numbers were pretty much the same.

joey1320

The reason why the coolant level rises when you rev the engine, its because you are increasing the volume/pressure, since the water pump is belt driven.

What you are describing is normal - up to a point. Meaning it shouldn't be shooting out of the radiator when you lightly tap the throttle.

If I was you, I would remove the cap, top off the coolant and properly bleed fhe system. Then just let the engine run, with the cap off for as long as you can. See if the fans come on time and monitor the temp gauge.

If you can run the engine at idle and bleed the coolant, and the temp doesn't shoot up. Then get a new cap and drive it and see what happens.

NotARaCist

iTrader: (1)

And while you're replacing the cap, inspect the radiator for cracks, damage, or leaks. The OEM radiator has shitty plastic end tanks that are known to have issues.

SonicC

I will try with new cap. I've tried bleeding the system previously, but bubbles never seem to stop - and I've bled cooling systems before that had air in them. Also engine temps never go over normal operating temperature and fans start normal.

I'll put a new cap over the weekend, drive around for a while, and report back.

One of the first things I checked was radiator and hoses. There are no leaks/puddles when I leave the car parked.

NotARaCist

iTrader: (1)

There doesn't necessarily have to be. If it's leaking "from the cap", it could be damaged just enough to be actually leaking from the plastic near the cap.

burnoutboy

iTrader: (22)

Comp tested a 97 EX the other day at 200-200-200-215 the other day. Seemed high but it tested that way twice.

Former User

To avoid thread lock, add car/engine information to your first post. See forum Rules sticky.

SonicC

Updated!

Former User

SonicC

So...I got the block tester from AutoZone and did the test twice, pumping that little bulb for about 2 minutes each time. To make sure this stuff works, at the end of second test I put the tester near exhaust and pulled some fumes, it turned yellow immediately.

I replaced the radiator cap as well, but haven't had a chance to take the car for a drive yet. Had it running for about 5 min. with cap on, revved a little, but no leaks.

Don't want to celebrate just yet...

NotARaCist

iTrader: (1)

Hmm, I'll try to remember to find the compression specs in the FSM for you when I get home. In the meantime, though, did you do that test with the engine at operating temperature, WOT? I'm fairly certain 120 is well below service limits, which if memory serves correctly is 135 and 10% variance.

SonicC

Test was done with engine at normal operating temps - per instructions. Didn't say anything about doing the test at WOT, tho.

NotARaCist

iTrader: (1)

Yeah, you're supposed to do the test at WOT.

SonicC

I watched a few videos and read instructions that came with it, no mention of WOT...

NotARaCist

iTrader: (1)

Yet another FSM page I'm going to have to post for you, when I get home.

Former User

A compression test is always done at WOT.

SonicC

I think you guys misunderstood me...I wasn't doing a compression test, that was previously.

I posted an update earlier with a picture of block tester with blue liquid in it. It wasn't turning yellow.