Was freeze-plugs, now head scratches...

[TylerDurden]

Hi folks,

I pulled my engine from the '91 ECO and cleaned a huge load of grease/dirt off it. Cleaning revealed that block has three shiny freeze-plugs which I presume are not original. I am now concerned that the engine has clogged block passages or other issues. It boils over when running straight water and idles ~220F using 50/50 coolant.

When an engine freezes, does a bunch of scale and crud get loosened and collect in the block?

It would suck to install this engine in my daily-driver only to discover later that my block is literally stuffed and prone to overheat.



Backstory:
I purchased the car (cheap) as a non-starter. It sat for a year before I bought it and sat a year in my driveway.  I purged the pump and the engine runs great from a bottle. Compression is ~425psi in all cylinders. The turbo spins, but is leaking plenty of oil into the downpipe. (The exhaust was broken off at the bottom of the downpipe.) The brake-lines are gone from rust, so I couldn't drive it around.

I flushed loads of grey silt out of the radiator.
I flushed out the engine and lines with a garden-hose and the water flows freely.
Running the engine with a new radiator, it boils over running straight water.
Running with 50/50 mix, the engine runs ~220F.
No gasses detected in the coolant.
Waterpump OK.
Thermostat OK.
Radiator fans OK.

Thoughts are appreciated.

[rodpaslow]

When flushed the engine lines, how much crap came out of there?  Did it have antifreeze in it or water?

[TylerDurden]

IIRC, the engine had very little coolant in it when I got it. I topped it off with water before trying to start it.

I flushed the system, first by jamming a garden hose into the reservoir -> pump line and ran the outlet from the head to a bucket (engine running). It was pretty clear, with a few black greasy flecks. Then I flushed the heater lines both ways with the hose and flushed from the pump's heater return line, through the engine and out the upper rad hose & heater flange (bypass hose pinched-off) . The outflow was clear.

[bajacalal]

Do a chemical flush.

[mtrans]

that all + I put fuel filter for clean.Best

[R.O.R-2.0]

that all + I put fuel filter for clean.Best

a fuel filter will do NOTHING to the running idle temps...

[R.O.R-2.0]

for sure the water pump is ok?

the impeller isnt spinning on the hub?

[TylerDurden]

for sure the water pump is ok? the impeller isnt spinning on the hub?

I couldn't get it to move relative to the hub by sticking my finger in there and turning the hub, so unless the heat loosens it, I think it's ok... I will check again, now that the engine is out.

[TylerDurden]

I couldn't get the impeller (cast) to budge, holding it with a prybar while trying to turn the hub by hand.

[rodpaslow]

At idle, I'm assuming you run it for 15 minutes or so and then it boils over.  Does the rad fan cut in before it boils over?

It's not a huge job to pull the coolant pump off.  I think if it were my car that would be the first thing I would do and make sure the outlet to the engine was not severely blocked-and run a hose in there an make sure it was coming out the end of the head, or the top of the head (hose back to top of rad).  If that's okay?? -Frost plugs next?

[TylerDurden]

Ja, plain water boils over (cap open) before the fans kick on.

Additional info:The ball-reservoir walls are opaque with black residue, but the horizontal baffle inside is relatively clean, so I think there was floating oil or dissolved hose in the coolant at some point. The tstat housing (outlet) and radiator had a light grey residue inside. Maybe someone tried sodium silicate? I've never seen a system where that has been used (it *can* work as a hail-mary).

I tested the thermostat and it is apparently mismarked as a 160F - it is not fully open and extending enough to block the bypass until 190F. That will explain the difference in the temperatures compared to my '89.

Measured:

Pump's t-stat flange to bypass flange: 38mm
Tstat flange to bypass block-plate top (closed): 31mm
Tstat flange to bypass block-plate top (open): 42mm

The older thermostat seems to have the potential for more movement, but the new/mismarked tstat has enough extension to close the bypass at 190F.


What concerns me are the signs of trouble: freeze-plugs, silt in radiator and black tank. Everything may have been resolved, but the thought of a block with rust and scale sitting around the bottoms of the cylinders is nagging at me. (My experience with small-block Chevy V8s was that large debris would not flush out of the drain holes and the heads had to come off for a thorough cleaning.) OTOH, maybe all the silt and crap got captured by the radiator (there was plenty).

Consider me paranoid.

 

[hillfolk'r]

Sorry im just postin.didnt read all the other posts yet...
those 3 freeze plugs are 36mm....
grey nasty crap in the cooling system?
could you have had a blown head gasket before?getting oil in your water....
at my old shop,our little trick to get the oil out of a cooling system was to get some cascade and mix it in some hot water...throw it in the rad and run it.....ya may haveta do that a few times...flush it out with water tho,dont leave that stuff in there after its gettin cleaner..
ok ill go read more up above




Ok update...black crap in the catchtank def sounds like oil...im a little suspicious of your head gasket condition.....i know those freezeplugs are shiny,but i think they are orig.
head gaskets can blow 18 different ways...oil into coolant,coolant in oil...combustion into coolant,,combjstion into oil....keep countin theres more...
and the overheat thing? Im still suspicious of your headgasket,hate to say it

[burn_your_money]

Ja, plain water boils over (cap open) before the fans kick on.

Have you tested the rad fan thermostat to make sure it's working right?

[TylerDurden]

Thanks for your replies.

I will do a chemical flush after swapping into the other car.

I will repeat the combustion vapor test too.

The fan switch tests ok on both speeds.


Now that the engine is out, I'm much more likely to pull the water pump to look inside the hole; but just as much to lubricate the bolts in case I want to change the pump later without removing the IP. Gonna replace the IM shaft bearings as well.

If the freeze-plugs look original, then I am less apprehensive about prior freeze damage/debris. The main concern is a trashed block. If needed, I can do a head gasket in the car. (Fingers crossed)

 

[92EcoDiesel Jetta]

Why is your cap open? It should be closed which raises the boiling point of the coolant.