Over the past week, I've had my first crack at rebuilding the top end of an engine on my 1997 Del Sol S. I replaced the head after dealing with coolant burn that would lead to overheating after about 20 minutes of using the car and me constantly needing to top it off.

Today, while putting fluids in the engine I noticed a fairly steady coolant drip coming form somewhere under the intake manifold on the side closest to the distributor. It ran down the back of the engine and dripped from the exhaust pipe hanger that sits under the intake manifold. With how much stuff is in the way, I couldn't isolate it to the intake manifold gasket, but it looks like that's a common issue with d16y engines so I pulled the intake manifold tried my best to clean up the manifold and head and reinstalled a new Fel-Pro gasket. I also disconnected all hoses on the intake manifold and reconnected them. After putting coolant in, the drip started almost immediately. All bolts/nuts are torqued to specs in the Hayne's manual.

Before doing the intake gasket installation for a third time I decided to start the car and do a pressure check to see if the head gasket was installed correctly. All four cylinders are reading the exact same 180psi.

The white smoke starts coming out of the exhaust within the first 30 seconds of the engine starting. It is by far worse than any coolant burn I had before replacing the head, so I doubt that it has much of anything to do with warping in the cylinder block. Otherwise the engine is running a little rough (sounds like a large diesel truck engine) but I have yet to set the timing, so that along with coolant making its way into the cylinders is likely the main cause. I also broke the downdraft O2 sensor when taking things apart, so I have it screwed in the socket to push exhaust all of the way through the pipe but it's not connected to the ECU and I have the accompanying CEL for the sensor.

Unless I'm looking at the wrong thing, I have these questions:
Should I get an intake gasket from Honda?
Is it possible that the head gasket is leaking but giving me consistent compression?

This is my first time asking a question here and not just reading from other's posts. Thanks in advance!

 

Did you rule out the possibility that the coolant leak that runs down the rear of the engine originates between the head/head gasket/block interface?

I recommend that you pressure test the warm engine and examine over time whether coolant appears in the one or more cylinders and also leaks down the rear of the engine. The latter would also permit you to pinpoint the location of the external coolant leak.

As you know, the original engine overheating may have warped both the block and head. Did you check the flatness of the block top with a precision straight edge? Was the bottom of the replacement head milled flat and leak tested? Did you follow the torquing procedure detailed in the service manual for the head installation?
Did you clean the head bolts and holes with solvent and a thread restorer to ensure that the head bolts were properly torqued to specification?

 

Yes you need to find the exact spot of the leak, perhaps remove the distributor and a few other non-water related parts for a better view.

It should be obvious but the intake manifold gasket can be put on backwards. There is a section with a rubber insert which goes over the water passage into the intake at the cylinder 4 end. Leakage there could be sucked into the engine and cause white smoke at the exhaust.

 

I haven't ruled that out yet. The coolant pipes that run along the back of the engine are preventing me from seeing where the origin might be form underneath the car and I can't see a leak through the gaps in the manifold.

I did a pressure check of each cylinder and they all held 180psi with no hissing sounds, radiator bubbling, or increase in the amount of coolant leaking externally.

I don't have a factory service manual but I do have a Hayne's manual. I did check flatness and clean both mating surfaces before installing. I used the following progressive torque settings in the factory required sequence: 14-36-49-49 ft.lbs. I did clean the bolt threading before installing.

If I'm not losing any compression in the cylinders, is it possible that coolant could still make it into the cylinders? Since the cooling system shouldn't be pressurized, I'm not sure how it could.

I just looked through the spark plug hole and can see some fluid on piston #4. The intake manifold is a little damp below the butterfly valve. I have a Fel-Pro gasket on the intake where the coolant hole has no special material, but the non-existent EGR port has a metal ring. Is this normal? And if these issues are more symptomatic of bad sealing between the head/gasket/intake would RTV be out of the question for sealing around the coolant hole?

If RTV is out of the question for sealing that hole, is there anything else I can check before tearing everything apart and doing the head gasket again? Also, is the honda intake gasket going to do a better job than the one I have?

Thanks for the quick replies!

 

Note that it's also possible that the leak originates from the distributor-side connecting pipe O-ring.

Forget about the good compression numbers temporarily. If you wish to locate the coolant leak, top off the cooling system with coolant and then place the cooling system under pressure. Then monitor the engine externally and internally (cylinders) for coolant leaking or accumulating.

Download the 92-95 Civic factor manual from the interweb. It has what you need. You absolutely require the factory manual to do the work CORRECTLY. There's no substitute.

 

Due to the volume of coolant in the cylinders I decided to go ahead and remove the head again. I rechecked the mating surfaces of both the head and block and neither had any discernible warping. After the weekend I'm going to get OEM head and intake gaskets, reassemble and see if there are any leaks. If so, I will pressurize the cooling system and provide an update here is that doesn't help me isolate any issues.

I found the factory service manual and it looks like I did everything assembly-wise to spec. Thanks for pointing me to that. My brief skimming when looking for it awhile ago made me think it would be nearly $100 to get.

 

Just an FYI. Checking for head and block surface warpage requires a precision straight edge, a good feeler gauge set, and some time and patience.

You can also find YouTube videos that demonstrate this important procedure.

 

Right, OP never stated how he checked for warpage.

 

I could have been more specific for sure. I used a 36" precision straight edge accurate to within .001" and a .04mm feeler gauge. I saw this diagram after doing the check, but everything I did followed the procedure.

 

there are quite a few hoses in the area you saw the dripping, I'd suggest looking at that.

 

Also have to check for warpage on the block itself, hope that was done?

 

Over the past couple of days, I got new gaskets for the head and intake. I was able to get the external leak behind the intake to stop, however I'm still dealing with coolant accumulating and burning in the cylinders immediately after the engine is started. I used a pressure tester today and set it to 16psi, a bit less than the max pressure I could find in the shop manual. Over the span of about two minutes it lost .5psi, so there is a small leak somewhere. After letting it hold pressure for 5 minutes, I looked through the spark plug holes. There was no more coolant than what accumulated when I started the engine yesterday. Using a remote starting switch and turning the engine over didn't affect the pressurization of the cooling system.

I did check the block for flatness again along with the head when I had them apart. This coolant leak is far worse than what I was dealing with before swapping heads, so I'd find it hard to believe that there's anything wrong with the block. After another inspection I couldn't find any cracks in the head.