My car has been plagued by an overheating problem. After going through all the cooling system accessories I finally pulled the head. Here is what I found.

1) Severe carbon buildup in the combustion chambers and on the pistons. Cylinders 5 and 6 were particularly bad (actually had ridges that seperated the quench area from the exhaust valves). I think this is a byproduct of the my run in with a lovely young gas station attendent who decided to pump my car full of diesel last year.

2) I found some rust buildup in a couple of the water passages where the head mates to the block/gasket.

3) I found three pieces of wire rod about the diameter of a coathanger, and each about a foot long in the the water jacket in the head.

Here are my questions

1. Which was more likely to contribute to the overheating? The carbon buildup or the partly plugged water passages.

2. Were the wire rods put in at the factory. My friend and I came up with three possible explanations: (a) they were placed there to prevent corrosion in the head (sacrificial metal) - not likely in my opinion because they weren't corroded. (b) they were placed there to prevent the water passages from becoming plugged up. (c) assembly line hi-jinks.

3. I noticed that there is a water passage at the front of the head/block that is blocked off by the head gasket. Why? What is the reason for this? Better coolant circulation in the head? What would unblocking it do?

TIA

rdb787@mail.usask.ca

**Plugged water passages, including a "too small" radiator. (Kinda acts like a plugged passage if you think about it)
:
: 2. Were the wire rods put in at the factory. My
: friend and I came up with three possible
: explanations: (a) they were placed there to
: prevent corrosion in the head (sacrificial
: metal) - not likely in my opinion because
: they weren't corroded. (b) they were placed
: there to prevent the water passages from
: becoming plugged up. (c) assembly line
: hi-jinks. (d) none of the above.

** The answer is (d), those are old casting "core wires". These wires helped the foundry workers hold all the waterjacket sand cores together as the sand molds were made & the mold poured. Pull them out whenever possible.
:
: 3. I noticed that there is a water passage at
: the front of the head/block that is blocked
: off by the head gasket. Why? What is the
: reason for this? Better coolant circulation
: in the head? What would unblocking it do?

** The cool water comes-into the block at the waterpump, most of it is suppost to flow through the block, cooling all the "barrels", then come-up into the head through those two large holes and flow forward. (a small amoult of cooler block water comes-up under each exhaust port through the small "steam holes", see diagram, cooling passages (6)directly accross from all the exhaust valves)

If you open-up that front or even the middle passage, the water flow will "short circuit" from the pump area, up through this hole and right back out into the radiator, without cooling the engine. This will "fool" your temp. guage to show "cold"(awash with cool water directly from the radiator) as the rear of the engine "frys".
I do admit that the factory is not real clear on this and even this diagram implies that the front passage is open but Leave it Closed! The only gasket "mods" under review by the racers is to enlarge the steam holes and put an additional stem hole at the middle point in an attempt to even-out the head temp, front to back.
DD

I don't think it is the rad. The rad I had in there before had worked perfectly with my last engine. The one I replaced it with is out of an early 80s M/R body /6 with AC. Wide, single core with the shroud. This helped the problem but did notcompletely fix it. There didn't seem to be a lot of blockage at the rear water holes and it appears quite clean in the head. I will check the steam holes as well and will also examine the matching holes in the block.
:
: ** The answer is (d), those are old casting
: "core wires". These wires helped
: the foundry workers hold all the waterjacket
: sand cores together as the sand molds were
: made & the mold poured. Pull them out
: whenever possible.

already done. I figured it wouldn't hurt the cooling to do so.
:
: ** The cool water comes-into the block at the
: waterpump, most of it is suppost to flow
: through the block, cooling all the
: "barrels", then come-up into the
: head through those two large holes and flow
: forward. (a small amoult of cooler block
: water comes-up under each exhaust port
: through the small "steam holes",
: see diagram, cooling passages (6)directly
: accross from all the exhaust valves)
:
: If you open-up that front or even the middle
: passage, the water flow will "short
: circuit" from the pump area, up through
: this hole and right back out into the
: radiator, without cooling the engine. This
: will "fool" your temp. guage to
: show "cold"(awash with cool water
: directly from the radiator) as the rear of
: the engine "frys".
: I do admit that the factory is not real clear
: on this and even this diagram implies that
: the front passage is open but Leave it
: Closed! The only gasket "mods"
: under review by the racers is to enlarge the
: steam holes and put an additional stem hole
: at the middle point in an attempt to
: even-out the head temp, front to back.
: DD

I suspected there was a reason that it was closed off and that it would have to do with water flow. Is enlarging the steam holes something I can do myself on this engine, or is that a race only mod?

rdb787@mail.usask.ca