Running Hot

[Petros]

the water pump is an easy replacement, and does not cost that much for a new one. If you suspect something is wrong there you might pull it off and take a look at it. if looks good you can use gasket sealer to put it back on. Or just replace it all together. Not likely it is a problem, so save it for last. It is a bit easier to reach with the head off, but not so much were I would replace it unless you suspect it.

Make sure the top of the block is clean and smooth, as well as the head surface, before you bolt it back together. A leaky head gasket can contribute to overheating two ways, if it can not develop pressure in the cooling system the hot places in the engine will boil the coolant away and cause it to overheat. the other is you are loosing coolant and when it gets low enough it will not have enough capacity to keep it cool. usually if it is leaking slowly it will keep the temp down until you loose enough to overheat. If it is leaky fast enough it will overheat within a few min, usually you get billows of white steam out the exhaust when it is that fast of a leak. pull the spark plugs and inspect the top of the pistons through the spark plug holes with a flash light, if the piston top is clean aluminum, you have a bad head gasket. It has been "steam cleaning" the top of the piston with overheated coolant.

[shambug]

Got the head off and partly cleaned. The pictures are from before I cleaned it. How clean does the head have to be, because I've been scrubbing for 2 days and it's about 95 percent off. I've used 2 cans of carb cleaner, alcohol and mr clean heavy duty scrub pads. I'm going to spend the rest of the day cleaning the head and block up and then I'll post pictures of them to see if you guys think it will be good enough to seal.

[irowiki]

HOw was the old gasket?

[shambug]

No obvious breaks in gasket but a warp in gasket by the number 4 chamber between water hole and chamber. I'm not sure if this was caused by the removal of the head but it does has excessive corrosion. I posted a close up of it above.

[Petros]

the head itself just needs all of the loose grit, grease and dirt off of it, it does not have to look like new. However, the gasket mating surfaces on head and block must look "new", down to bare metal. After cleaning use 200 grit sand paper and a flat metal block or plate as a sanding block (a granite tile also works well), than finish up with 300 or 400 wet and dry, use soapy water on the surface to "wet sand" the surfaces. Final clean with carb cleaner. There should be no marks, stains, old gasket, discoloration, anything on the gasket mating surfaces. Should look like new metal on both head and top of block.

See my Repair Guides thread on the topic. You will also need to get the head bolt holes, and threads very clean with the correct size bore brush (looks like a stiff bottle brush, get it from auto parts store).

[xirdneh]

if you use granite tiles you ought to check them first to make sure they are flat
i bought 4 the other day and all were not flat ( i figured the odds would be good that at least one was flat)
i will be taking them back
this time i will bring a straight edge and check them at the store
there are some videos on youtube that show several ways to clean off/flatten the head
one used thick piece of particle board with some handles glued to the top
one used a large piece of granite or something like it (countertop) with big piece of sandpaper glued to it, he still had to check to make sure granite was flat) if the table it sits on if not flat the granite will bend just a little bit to suit the table

[shambug]

What about a piece of glass if Im careful, or a piece of glass with plywood backing. I ordered a straight edge to check the granite titles they have at the reuse supply store but it wont be here till the 3rd and I was hopping to get her running as fast a possible, without compromising the job. Using a normal 12'' thick metal ruler and feeler gauge I cant find any warpage on head or block. The piston does come about 1/100'' above the block gasket mounting at TDC, should I sand that down to. They only had 220 and 600 grit sand paper left I figured Id make it work.

[xirdneh]

check your straight edge too
set it on something flat then flip it over
if there is no gap on one side but a gap on the flip side, it is not true
you can still use it but use the side with the gap (in the middle)
when you use the straight edge the gap measured with the feeler gage would be divided by 2 to get the actual gap on the head or granite tile you are checking
not the best but a make do situation

went back to home depot and returned the granite tiles
found some marble tiles that were perfect (flat)
glass should work fine if thick enough

[shambug]

Got the new head gasket in and went for a very short test drive. Thanks for the repair guide Petros you saved me another thousand bucks. Only thing I found misleading was the very hopeful 4 hour estimation, I would say I put about 30-40 hours into it, mostly sanding. I modified the head to include the "Jets", but did not modify the head gasket as I didn't have the proper drill sizes. Reset the ignition timing to 10 BTC, it was before just reset it to make sure. Seems to be running as good as before. I will go on a longer test run tomorrow and see if she still overheats. But you can be sure im not ever going to let it get overheated ever again!!! I literally have nightmares now about not being able to stop well the car is overheating.

[marlinh]

Congratulations on a job well done.

[shambug]

Still overheating
I am getting hot air out of the heater so I figure the water pump is pumping water. With engine on, radiator top hose is hot well bottom hose is cold and I can run water though it so I figure radiator is good. Just replaced the thermostat. Whats left?

[irowiki]

Bad sender, bad wiring, bad temp gauge? How do you know it is overheating? Has the radiator been replaced? Does the heater help when it runs hot?

[dlb]

dang! sorry to hear it, shambug.

did you ever replace the rad cap? is it still puking coolant out the overflow when it overheats?

i wonder if there could be a blockage in passages through the head and block.

[shambug]

New temp gauge and rad cap, checked wiring. I know its overheating because water was coming out the overfill before I did the head gasket, I didn't let it get but a tiny bit over the center on the gauge this time. I sprayed carp cleaner down all the holes in the head and none of them seemed clogged. This might sound stupid but what direction does the thermostat go in?

[Petros]

t-stat can only go in one way. it is normal for it to get slightly above half way up the gauge, usually I find on mine the fan kicks in when stopped when the needle is at about the top of the little thermometer on the gauge, and than comes down fast to just under it.

Not likley the passage ways are plugged, the sytem is simple if everything is working right the only thing that will cause it to overheat are poor radiator performance (usually if you flip on the heater fan the temp drops fast, it adds cooling capacity when you do that and this would indicate poor radiator performance due to scale build up or blockage), bad T-stat, or something limiting coolant circulation (including pump, but that is pretty rare). Also, a leaky head gasket, hose or rad cap will not allow it to build up pressure and also limit cooling performance because the coolant will boil off early at lower temps.

You might be okay if your only symptom is the gauge getting halfway up. Might be worth buying an auxilary temp guage with actual numbers on it and check what it is actually doing and compare with factory specs on coolant temp.

That time to replace the head gasket is what it normally takes me to do it, though I have done this job perhaps 20 or more times on these engines for my self and others (I have actually completed a head gasket job in 3 hours, mostly 3.5 to 4 without hurrying). A newbie would take perhaps twice that, and it does not including finding the tools, parts and other things you will need to keep working, nor breaking free and removing stuck bolts or rusted parts. Also, cleaning off an old head can take a while if you do not have a good way to clean it, and old gasket is really baked on. If you have to surface sand the head to eliminate the warp, that could take all night by itself. Usually I have found the head is not warped, it just needs the old gasket removed.