Steam Powered Z???

[rossiz]

actually i think i may have a blown head gasket. nice

replaced a leaky radiator (it was toast) and when i got her all filled up i noticed billowing white plumes from the tail pipe.

also got a geyser shooting out of the little vent hole in my coolant reservoir tank.

smells like burning propylene glycol...

i think mr. murphy caught up w/me very quickly.

so it looks like maybe the head's gotta come off sooner than i had hoped.

anyone done this recently? any tips?

[240260280z]

Look at your plugs.

Also crank the motor with the plugs out and EFI depowered. See if coolant comes out.

Check compression cold and also hot.

Could be a cracked head. N47's like to do this...... what's the line on that ZX engine?

http://atlanticz.ca/zclub/techtips/head/crackedhead/index.htm

[Captain Obvious]

Awww man..... What the heck??? :ogre: Murphy must really be pissed from that sheet metal screw thing in the rear. Time to reset that two trouble free weeks counter!!

Was there some specific event that preceded the failure?

Been quite a while since I did a head gasket on one of these, but if you've done others, this one is pretty simple. Don't snap off the bolts holding on the thermostat housing and don't drop the timing chain. Oh, and when you're yanking the head up and it just won't budge like you missed a bolt somewhere, don't forget about the small one (or two?) around the front cover.

[rossiz]

blue - just checked your cracked head tech post, and now i don't feel so good...

now is so most definitely not the time for a major deal/engine swap - kids graduating, college payments starting, i just need the car to run so i can go to work each morning.

so can i drive it as is and carry a gallon jug of water with me, or will this ruin things below?

there was no "event" to speak of prior to this happening, other than me replacing the radiator. i'm wondering if there was localized overheating due to air in the system? the temp gauge never went past the center though...

[240260280z]

Good news is that a head swap or gasket replacement is easy for you and not expensive. Even a head skim (warped) is cheap.

Your first step is to localize and identify the cause. Driving may be ok. That is a lot of steam so the police may raise an eyebrow.

Re-torquing head bolts may help a bit if it is the gasket.

Also check oil to see if coolant is entering.

The fluids flow with pressure and there are a few combo's to note:

oil will go into coolant when oil is pumping as the pressure is higher

coolant will go into oil when car is stopped but hot (oil pump is 0psi and coolant may be up to 13psi)

coolant will go into combustion chamber after car is turned off but off (coolant may be up to 13psi)

coolant will go into combustion chamber on intake stroke (chamber is -15psi and coolant may be up to 13psi

combustion gas can go into rad during driving on power stroke... the intense pressure makes a geyser if you have the rad cap off

Oil usually goes into combustion chamber

- from below when running (bad rings/walls)

- from above when off (valve seals)... as you know

- from above when over run (high rpm vacuum)

[SteveJ]

so can i drive it as is and carry a gallon jug of water with me, or will this ruin things below?

If coolant is getting into the combustion chamber, it can get into the oil. Water won't lubricate the bearings or other moving parts very well.

[rossiz]

tried to drive to work - no go. 3 miles down the road coolant came spraying up through the hood vents and onto the left & right corners of the windshield. pull over, dump out half of the maxxed out coolant reservoir, pour half gallon of water into the radiator, limp home. i will be using my son's 4runner and/or my bike to get to work until this is sorted.

will pull the head and see if it's a gasket (hope springs eternal...) or if i need a new head.

funny thing is i was getting pretty excited about how great it was starting and how the hot-start issue had vanished after i solved my low fuel pressure problem - was actually gloating every time i'd get in the car and fire it up - especially running errands on a hot day.

pride cometh before a fall.

[motorman7]

Saw the topic and thought this car was perhaps the subject....a real steam powered 260Z

[240260280z]

Try starting with the hood up and rad cap off... if you see old faithful then you have combustion going into coolant...probably just the head gasket.

[240260280z]

FYI: http://www.classiczcars.com/forums/tech-pubs-howto/42420-77-280z-head-removal-%5Bstep-step-photos%5D.html

[rossiz]

decided to get right into it - thanks to blue for the great tech article, i got the head ripped off in 2 1/2 hrs.

also the entire exhaust system and a few other bits. i had ordered an msa 6-1 header (supposed to arrive later this week) and a stud kit, but this was before the latest disaster - i was planning on taking my time, picking up parts and doing the work a bit later, but heck, no time like now, eh?

i was really lucky in that there were no frozen bolts, except for a couple on the exhaust flanges but that's all scrap anyway. one head bolt snapped, but it broke in the middle and i was able to twist it out w/vice grips - lucky. the head looks horrible - crusty, full of carbon, exhaust liners look like a crazy science experiment, with all different color crud caked to them. the pistons look in surprisingly good shape, but 3 & 4 have some light pitting on them in a similar pattern, in the center that looks like it might be from some funky burn issues. the head gasket doesn't show any clear signs of being blown, but i haven't scraped it off the block yet.

faced with the time, effort and uncertainty with fixing up the head, i think i'm just going to spring for a re-built replacement. i've seen a couple for ~$500 complete w/cam, valves, everything all set up and fresh. i'm guessing by the time i replace the valves, re-do the guides, skim the surfaces, magnaflux, repair cracks, grind the seats, replace springs, i won't be far off from that cost anyway.

thinking of going for a cam while i'm at it - any recommendations for the grind?

couple of pictures of the process and some of the "interesting" discoveries - i'm actually glad to be doing this, as i found some things that were really sketchy and never would have known about them otherwise...

sawzall does the job

egr tube was broken at exhaust manifold - fell off in my hand

end of manifold had cracked off and PO had filled it w/some kind of epoxy/putty/filler crap

PO packed the filler all the way into the egr cavity - i chipped out LOADS of the crumbling, chalky stuff - gonna weld it shut

intake off, ready to attack exhaust (w/the sawzall)

easier to cut the downpipe than mess w/the frozen studs

tools of torture

head off - cylinders were full of water that drained from the head

sopped up the water with paper towels and sprayed some wd40 in to stave off rust

i'll post some pics of the head tomorrow - it looks pretty hopeless...

[240260280z]

Looks like water was going from cylinder 4 to 3 both over and under the gasket (water/rust marks in pics below). The dimple for piston forward orientation may be part of the fundamental problem with these engines and hot gas blasting the gasket.

I think you will find cracks in the head in 4 and maybe 3.

If you get a new head get an N42 with no liners to avoid cracks

Also if you get a high lift cam you may need new lash pads to get the correct wipe pattern on the rockers.

Edited June 10, 2014 by Blue