Add to the list of suspects:


1. Heater hoses. An array right along the fire wall.


2. the vacuum operated heater control valve. Center of the fire wall.


3. The heater matrix. deeply hidden along the firewall, but, ion the cabin.


I second Lagonia's suggestion. Pressure it up and inspect...


Carl

 

There's a hose on the underside of the intake (inlet) manfold that's IMO impossible to see from above the engine, and nearly impossible from the bottom. (If it were my car, this would be the hose that would go first.) If that one has a crack or even just loose connections, it's going to be very difficult to see (and even harder to replace without removing the manifold).


Two hoses that connect to a metal pipe that runs under the intake manifold, between the manifold and the block. The rear end goes to, IIRC, a port in the firewall; the front end goes to the back of the water pump. Might check those connections and the condition of the hose. At least you can get to them.


No coolant in the oil pan? That would be my worst-case scenario.

 

Ok, I'm an idiot. The gasket on the coolant tank was off to the side. I can only assume coolant was gushing out of the overflow hose every single drive.

I tried to pressurize the system (bicycle pump and adapter), and kept hearing a leak right under the tank and finally noticed fluid running out of the overflow hose. I straightened the gasket, and found a small leak in that hose under the manifold, but couldn't fix it. (I'll buy a new hose eventually.)

At any rate, took it on the same 10 mile or so drive, came back and let it cool down enough to open the coolant tank, and it was all under pressure and full.

Conclusion: I now know a lot more about the cooling system...and I'm kind of an idiot.

Now, to that EGR system and smog pump thingy. I've noticed that the air line going up and over the engine falls off if I touch it and doesn't seem to do anything. Does it really matter if I disconnect the whole thing? Is some part of the engine management system looking for signals from the box on the back of the pump?

thanks for all your help.

 

Air Injection System, actually...not EGR. Your car doesn't have EGR.



Often the pipe rusts out and nearly falls off on its own.

Many have removed the pump and pipes, no big deal. You have to plug the 6 holes in the cylinder head, though. Others will chime in on various methods of doing so.


The black box on the rear of the pump is just a diverter valve. It isn't very smart; no communication with the ECU. It simply opens/closes as ordered by the air switching module on RH fenderwell.

Cheers
DD

 

What is bolted to the rear exhaust manifold and then runs around behind the head and is attached to the back of the inlet manifold then?

 

Hmmm. I dunno.

USA market Series IIIs did not have EGR. But Australian, Swiss, and Swedish market cars had it.

Sounds like you might have a gray market car! Cool!

Send some pics of the car and the pipes.

Cheers
DD

 

I should've said that Studentper, from Kansas, might have a gray market car. I'd like to see pics of *his* car because, if HE has EGR, it's probably a gray market car

Cheers
DD

 

No it was my bad I miss identified the air injection as EGR. Both of my exhaust manifolds have the big bolts in the holes at the bottom and no pipes coming out to going around.

 

My bad, didn't know US market missed out on the EGR system

 

Well i wouldn't say I've been missing it bob.

 

True, EGR in itself is OK. But, not having one to clutter up the engine bay and go tango up, is good.


Learned something, Those big plugs at the manifold flange are for EGR, when fitted? Always wondered why! Why, I wondered? Haven't the slightest!!!!


Carl

 

Unfortunately, the car is back to going through about 1/2 gallon of coolant every 50 or so miles, and none of it is on the garage floor. After an evening of letting the engine cool down, the system still has alot of pressure in it when I open the cap on the brown expansion tank. I can't think of anything other than a blown head gasket (or cracked head).

Any other thoughts?

thanks

 

Hi Studentper,

Bummer.

Water and oil don't mix, so I would be checking for water in oil (Engine) and oil in water (Radiator).

When the two come together in a working engine you get a grey milky sludge.

Maybe a bit hard to see in the coolant reservoir if there is no water to see, but look for an oily film on top of the water and or a sludgy residue when you remove the cap.

Pull the dipstick and look at the colour of the oil on the stick. Light brown, new oil. Darker brown, OK. Black needs an oil change. Grey milky streaks, you have water in the sump.

Check the pressure rating AND condition of your radiator cap.

Wrong pressure, water gets out whilst driving.
Worn rubber seals, same thing. ( I posted a thread last year about this).

What condition is your radiator and hoses?

Radiator could be weeping under pressure.
Hoses could be doing the same.

Good luck,

Nigel

 

One more place to look. An atmospheric expansion tank is located just behind the left front outboard head lamp. If over loaded with coolant, it will dump to the ground.


Too much coolant is not quite as bad as too little, but, still wrong.


Carl

 

I don't think I have an atmospheric tank. I traced the overflow tube from the pressure cap and over the weekend, i put a bag over the drain tube in the wheel well and ran the car around. The bag was dry all day. (I do still have to check the coolant to see if the level fell.) The coolant loss amount varies wildly, and I never see it on the ground. The oil looks fine. The coolant a little messy from the stop leak i hoped might delay the head gasket replacement.

 

So I think I've eliminated an external leak. A naïve question, does this mean that the head gasket must be blown and the coolant is being burned up?

The car burns about 1/2 liter every 50 or so miles (which is all I really drive it), and I'm inclined to just leave it alone and maybe deal with it in the winter. Bad idea?

 

Pressure in the cooling system after cool down indicates combustion gases are getting into the coolant passages. Normally this indicates a head gasket failure.

If your car is the last of the line (1987 is very late), then it will have the slotted block that was the modification to prevent block cracking between the bores. This then prevented premature head gasket failure. However despite this, it is unusual to get beyond about 80-90k miles without the gasket going.

There are now electronic testers that will detect combustion gas products in the coolant, so you need to go to a shop that has this equipment. A combustion chamber pressure test may also indicate where the gasket has failed.

 

Yeah, sounds like a head gasket.

I drove mine for several months with a leaky head gasket....although consumption hadn't yet reached the level you're experiencing...with no ill results. The only problem, besides having to top off the coolant, obviously, was rough running every morning. After shutdown each evening the coolant will dribble into the cylinders overnight and took 30 seconds or so to burn off the next morning.

Do be mindful that the leak might well become bad enough where the cylinders can become washed out and the oil contaminated.

Cheers
DD

 

A common trick is to use an exhaust gas analyzer to 'sniff' the coolant for hydrocarbons.

Another method is to use a leak detector kit....which has a dye that changes colors when exposed to hydrocarbons.

https://www.summitracing.com/parts/o...FQiSfgodUfQPZg

Cheers
DD

 

A TK tester is the go ^ basically tests for hydrocarbons.

If you have access to a cooling system pressure tester, give that a shot, and remove the spark plugs as well and if you have access to a borescope, inspect the piston tops to see if one is "steam" cleaned more so than the rest, another good indication that the headgasket is leaking between a coolant gallery and the combustion chamber.

If the pressure tester does lose pressure and there's no visible leaks, then crank it with the plugs out and watch to see if coolant is spat out of a plug hole.