[DMCForum] Re: damnit to hell (my poor engine)

["therealdmcvegas" <dmcvegas@xxxxxxx>]

--- In DMCForum@xxxxxxxxxxxxxxx, "Matt Spittle" <mds328@xxxx> wrote:
<SNIP> 
> Will running a coolant pressure test verify if I have a blown head 
> gasket?
> 
> thanks,
> 
> Matt
> #1604

Most definetly. You'll be pressurizing the cooling system, and forcing
water out of any leaks that you have. I had lots of coolant in the
"Valley of Deat" too, when one of the O-Rings on the Y-Pipe finally
rotted away, and allowed fluid to flow out freely. So you'll want to
snag a couple of new rings down at the local autoparts store when you
pick up the pressure testing kit. BTW, don't bother looking for the
rings in the aisle. They're in a box behind the counter.

But first, let's talk about what causes a head gasket to prematurely
fail. Heat is the enemy here. And you know that if you severely
overheated an engine, the cylinder heads warp and seperate themselves
from the headgasket. Obviously at that point you need to replace both
the cyliner head, and the head gasket. But, there is also another
silent killer of headgaskets, and it too is caused by heat.

Improperly bled cooling system: That's right. If you've got air in the
engine, you're gonna SEVERLY shorten the life of the headgasket. It
works like this. Cast Iron cylinder sleeves will heat up and expand
and a far slower rate than the Aluminium cylinder heads. However, when
we have coolant flowing across them both, the heat is gently
transfered between the two, and they both heat and expand at a much
more syncronized rate.

But air inside the cooling system negates all this. Water doesn't flow
across the surfaces evenly, and pockets of air them become steam
pockets. Now keep this in mind: Steam is a gas so it rises, and it's
the aluminum cylinder heads up that are on the top. The water below
may only be like 120°F during the warm up, but the steam pockets have
already hit 260°F+! So the Aluminum expands much more quickly than the
Cast Iron below. What happens here is that the head gaskets are slowly
torn, because the two sides between it are shifting in different
directions.

And DeLoreans are tricky to the average mechanic, when it comes to
diagnosing bad headgaskets just by sight.

Because of that damn valley under the intake manifold, it's easy to
believe that the car has a bad head gasket. You leak out fluid, but it
never drips below the car. Instead, it collects up above, and gets
boiled off. And then when a car isn't always run up to temperature,
the condensation inside is easily mistaken for coolant in the oil.
Although I too have concerns about that crap in the oil filler cap for
your engine.

Do this:
Step 1. Pressure test a FULL cooling system. 14½ PSI for 15 minutes,
and the fluctuation should be minimal, if at all.

If no leaks detected, move on to step 2. If leaks are found, repair
them before proceeding. Remeber, you're dealing with coolant hoses, a
radiator, engine block, AND the heater core inside. So check all these
areas IF the pressure isn't able to maintain itself.

Remove the rocker covers, and pull the oil drain plug. See if any
water sprays, or otherwise visably drips out of any of these places.
That'll find out what's going on with the engine.

Step 2: If/when no leaks are present, reassemble the top end with new
seals, hoses, etc. Use silicone hoses for the water pump, new rubber
tubes for the vacuum lines, new orings for the intake manifold, new
oil resistant hoses for the breather tubes, etc. SEAL EVERYTHING! Make
certain that there are no vacuum leaks.

Step 3: Disconnect the Oxygen sensor from the ECU wire, so that the
engine will stay in "limp mode", and won't fiddle with the O2 mixture
on you. Start the engine, and see how she runs. Since you had vacuum
leaks before, you're prolly gonna need to adjust the CO mixture to get
the car running right. So if you need to fiddle with it right now to
get the car running right, that's OK.

Step 4: Once the engine is cool, flush it with this (2nd from the bottom):
http://www.berrymanproducts.com/Default.aspx?tabid=139
This is POWERFUL stuff. It dissolves anything (including styrofoam),
and will clean out your motor. You'll only need about &#8532; of the bottle.
Pour it directing into the crankcase, and idle the motor for about 7
minutes. Then shut the motor off, and drain the oil & cleaner out ASAP.

After that you can drive the car to your local old skool Volvo
mechanic where you can reattach the O2 sensor, and get the CO balanced
on the motor. But I would first add that you pour some Techron into
the tank, and burn out the old gasoline first, and refill with fresh
before tuning the CO on the car.

-Robert

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