Do I have a cracked head? Coolant on the resonator.

[65 Lotus]

L.O.T.U.S.

I have a stock twin cam, no porting or polishing. It has the original-style 4-into-1 cast exhaust header and a downpipe with the resonator.

When the car sits for a while (a couple of months), I end up with a little puddle of coolant on the top of the resonator, maybe a teaspoon's worth.

I don't have bubbles in the radiator and the oil is fine as well. No white smoke in the exhaust. All I can figure is there's a fine crack between an exhaust port and a coolant passage and it slowly weeps out over time.

I havn't pulled the header yet to have a look. Has anyone ever seen this?

[bitsobrits]

Scott

Much more likely it's a weeping leak around your heater valve port or temp gauge port located next to the thermostat housing. Take a close look at the bottom of the thermostat housing area. A mirror helps.

To test for a slow leak here, when you park the car, tape a clean folded paper towel to the bottom of the housing, and see if that catches the coolant.

[65 Lotus]

Thanks for the reply. I've verified it's not coming from the outside, it's definitely coming down from the inside of the header.

Everything's bone dry until you get to the joint between the header and downpipe. The clamp is moist as well.

[types26/36]

On the MK1 head there is a couple of welsh plugs on the side.....it couldn't be coming from one of those could it?

[65 Lotus]

Checked those as well, all dry.

[types26/36]

.....and the one at the back?

[65 Lotus]

Looks good.

[robertverhey]

hi do a cooling system pressure test (search forum on "stant"), that can introduce pressure into the system when hot or cold. You'll soon see where it's leaking

Robert

[bill308]

You could also add a dye to the coolant which will flouresce under an ultraviolet light. Auto parts sources can provide a kit to do this for coolant and also oil and AC fluids.

Coolant from a small or slow leak may evaporate before its source can be detected. The dye should leave a definitive residue.

Bill

[Quart Meg Miles]

Scott, your first post and subsequent "all dry" responses suggest a crack between water and exhaust port resulting in water dripping down inside the manifold, then seeping through the joint to the resonator. I suggest you take the manifold off and look for wetness inside it.

[65 Lotus]

Thanks Meg:

The plan is to pull the manifold, but we're at the end of the driving season here in Ohio (for me anyway, no hood OR heater!).

Was just wondering if someone was familiar with that very failure mode rather than wonder all winter. I don't believe I've ever heard anyone mention it.

Not having seen it, it doesn't sound like a repair that would take very well to welding, what with the exhaust port expansion fatigue cycle every time you drive the car.

[JJDraper]

Sounds similar to a problem I had earlier this year..

elan-f15/rats-losing-coolant-t24742.html

The coolant dripped down the bellhousing and onto exhaust, which sounds a bit like your symptoms.

Jeremy

[collins_dan]

I have a leak in the back left corner between the block and the head. It's head off, new head gasket for me this winter. I'm trying to avoid Jeremy's puff of steam. Will make a couple of other changes at the same time; ceramic coat headers, sprint cams, one intake valve shim not right, and cam follower has a nip out of it from cm lobe. Don't ask. I did try replacing head bolts with ARP and tighten to 70, but didn't solve it. Dan

[cal44]

It is nice to notice I am not the only one. I got so mad I still haven't done anything to fix it. I'd rather stew and feel sorry for myself.................

Mike

[AHM]

On the MK1 head there is a couple of welsh plugs on the side.....it couldn't be coming from one of those could it?

That could be the problem... Welsh plugs are bound to leek and will definately weep when the Rugby is on!