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1983 280zx turbo engine


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Posted (edited)

fyi, I ran it and it seems to have survived despite my tool abuse 🙂

new oil in site glass looks nice and clear, vac was good, no odd noises. perhaps dodged the bullet, 

can I borrow you milling machine, want to try a new way of chopping up chlorine tablets for pool use...

Edited by Dave WM
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39 minutes ago, Dave WM said:

you pump got DM'd

Haha!!! I'm going to do my best to make that stick now.  And good luck finding someone to let you borrow a mill.    ROFL  !! 

And glad to hear your pump seems to have survived the ordeal. I'm not surprised. It's not like you ran it for an hour with the milkshake in there. Just a couple seconds and you got it changed out now. I'm thinking it should be fine. Might want to change it again after a shorter than normal run interval just to be sure?

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1 hour ago, Captain Obvious said:

Haha!!! I'm going to do my best to make that stick now.  And good luck finding someone to let you borrow a mill.    ROFL  !! 

And glad to hear your pump seems to have survived the ordeal. I'm not surprised. It's not like you ran it for an hour with the milkshake in there. Just a couple seconds and you got it changed out now. I'm thinking it should be fine. Might want to change it again after a shorter than normal run interval just to be sure?

forsure, after next time I use it will just drain again. I did run it for a few minutes, oil looked clear, but oil is cheap so why not.

got the rest of the plugs in, demo video of using the tool coming. I did have one issue you may want to check on yours, the shoulder of the tool was just a tad wide for the plug by the oil sending unit. there is a cast in boss that is just a bit closer than anywhere else to the opening. My tool got hung up (will see in the video). Off video I went back and filed it for clearance, then used the tool again to make sure it was a flush fit. I also checked the depth of the edge of the plug to the surface of the block. It was close enough that I did not feel any need to touch up the tool, the block is pretty ruff and getting a precise measurement using it as a ref seemed silly. I am sure its within spec if I knew what they were on that.

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  • 2 weeks later...

I was able to find a brand new OE turbo oil feed line from Japan. Came it today looks like a perfect fitment when compared to the old one. All that is left to do is put the turbo engine on the NA test stand and install the dizzy and the intake manifold. I already attached a spare exhaust manifold , T stat housing, and alternator with fan belt and pully. Last time I ended up swapping out a lot of stuff from one engine to the other, this time I am going for a faster turnaround time to test. It will prob be a few days as its just so dang hot its hard to get motivated to do the heavy lifting of moving engines around. Will see how long I can hold out (Stimpy guarding the red button at the end of "space madness")

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good news bad news...

good new is I got it all back together, no more brown anything including foam. Bad news same thing with the exhaust gases in the rad. I just cant figure out where its coming from. I looked at the block cyl walls when it was all apart, no cracks, it would have to have a crack there for gas in water jacket. The head also looked fine, again no cracks. This leaves the gasket as the only culprit (or warpage the gasket can not handle). The test with the straight edge were well within spec, and there were no defects noted on the sealing surfaces (block or head). So my only guess is I did not properly prep the surfaces and/or did not torque correctly. I retorqued after the inital run to 65ftlbs in the correct sequence. they took a tiny bit of torque. tested again, same thing green then pale yellow. I confirmed the test kit on the good engine so I know my process is correct. 

Next up will be to pull the head again and try a different gasket. I have an NOS aftermarket gasket, looks like asbestos infused, will try again with clean surface prep and torque sequnce in 3 stages. 

If that fails I my just bag the project for now, or maybe try installing the turbo on the good engine with the MN47 head. 

Other interesting news, I installed an O2 sensor in the bung that is cast into the manifold I used (had to plug it anyway). hooked up my analog VOM (simpson 260), and was able to get the voltage right at .5v by adding a bit more flap (just push it in) while running. I seems the setting is a bit lean, I may have some vacuum leaks or maybe that is just the way it is. the voltage .5 during the start up (when the enrichment is higher on a cold engine) but tapered off to near 0 as it warmed up. Adjusting the idle blead did not help (again vacuum leaks were probable). anyway the vac was about 15hg when meter read 0 volts, manual enrichment to .5v and the vacuum goes to more like 18hg. Clearly a sign of a better A/F mix. 

the O2 is a cheap bosch single wire i think refered to as a narrow band, regardless I can see how something like this would help with setup of the FI on one of this old open loop FI systems.

I am thinking of coming up with a circuit that is 0v at .5v from the sensor with +/- as it goes from 0 to 1v, with a variable output voltage on the +/-.

that could be fed in series with the output from the AFM wiper, making a closed loop system with a single mod to the wire harness. IIRC an op amp maybe involved to allow for the +/0/- output adjustable for voltage so the correcting voltage could be varied in amplitude so as not to overwhelm the stock AFM reading.

 

 

 

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Cylinder 3 and 4 exhaust valves are next to each other in the head, this is a design flaw and a good place to look for cracks. Have you had the head checked by a shop for cracks? That may be your only option. 

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14 hours ago, kickstand80 said:

Cylinder 3 and 4 exhaust valves are next to each other in the head, this is a design flaw and a good place to look for cracks. Have you had the head checked by a shop for cracks? That may be your only option. 

I will pull the head soon, will take a look, see if I can find a shop that can do for me. Thanks!

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Posted (edited)

Not sure exactly what it looks for. the puzzling thing is I sorta went thru this with the Non turbo, one day went out and test it again and IIRC i tested ok with the MN47 and then did with no changes made. Never failed since (i have tried it many times to confirm). Its NOT overheating (stayed right at 180-185 max on a super hot day with air temps over 100f, no thermostat mind you but no shroud either and not the best fan placement with respect to the rad.

I will try filling the rad up to the top, then starting and see if water boils out. I think I have seen where if gases are getting in, esp on a cold engine then the water will quickly overflow the filler neck as gas displaces coolant.

Edited by Dave WM
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How about pressurizing the cooling system and waiting to see which cylinder fills with coolant.  Watched a youtube video where the guy forgot and left his pressurized overnight.  The leak area was apparent.

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1st off tic is gone, pulled the pivot, reassembled under oil bath, all good.

Now the odd stuff. installed T stat, put funnel in rad, made sure it was the high point, filled to the max, no instant overflow. as the engine heated up I got a slow expansion and push out of coolant but no bubbles. by the time it hit about 185f it was just a bit of water coming out. Not sure I understand how that could happen unless there is gas filling somewhere, but decided to do the chem test again, before draining coolant (with it still running) I just pulled some garage air thur the test kit, opps blue is starting to turn green....

So before ANY more messing the engine is going out to the sidewalk for the next test. I cant imagine that enough exhaust gases were accumulating inside an open garage, but before any more moves, its going WAY out in the open air. Perhaps some of my recent decisions may be explained by the garage air test.........

ZH I will add that to the list of to do IF i get another L after an OUTDOOR test of the chem test.

 

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3 hours ago, Dave WM said:

but decided to do the chem test again, before draining coolant (with it still running) I just pulled some garage air thur the test kit, opps blue is starting to turn green....

Interesting observation. I wonder how may blown head gasket have been replaced due to too much exhaust gas in the garage!  

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leak down test done, passed with ony about 5-8% max loss. I suspect the combustion pressures are way higher so doubt I could pick up on a small leak.

I am going to try the top off with water test again. seems like NO water should flow out of the rad top on a cold start for at least a few min. IF any comes out at all then it seems must be gases displacing water. I figure it must be done cold to avoid any trapped air in the water jacket heating up. I assume IF no air at all in the water jacket, NOTHING should overflow as I dont think water expands from heat, at least until it shifts into steam. 

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53 minutes ago, Dave WM said:

seems like NO water should flow out of the rad top on a cold start for at least a few min. IF any comes out at all then it seems must be gases displacing water.

I dont think water expands from heat, at least until it shifts into steam. 

Water does expand with the heat. Just not as much (volumetricly) as gasses do. So even if there isn't any air in the system, the water will expand as the system heats up. And that expansion will start as soon as the engine is started.

Now granted... If there is air trapped somewhere, or if you do manage to boil some of that water, it will expand orders of magnitude more than water. But even just the water will expand (even if it doesn't change state).

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roger that CO. well I will have the videos soon, both of the water expansion and the chem test. Not looking good... let you guys have a look. tell me what you think.

will post here soon.

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here is the water overflow test. Note I did the same test with my car that does NOT change the fluid color, and I had the same results, water started to over flow within the same time span as this video. So as CO mentioned, the water apparently was expanding enough to start flowing with out the introduction of gases (in my good engine in the car).

 

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Posted (edited)

going to try adding some UV coolant dye to the rad, pump it up with a pressure tester, let it sit for a long while, then spin with plugs out and see if any dye is expelled thru plug holes. I tried already with pressure and then examine with borescope, but its not the best and could not really see well enough to call it. I figure the compression stroke will aerosol any accumulated coolant and spray will show the dye. I will spin the engine with the plugs out to hopefully disburse the dye, that may not do it though.

Edited by Dave WM
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2 hours ago, Dave WM said:

I figure the compression stroke will aerosol any accumulated coolant and spray will show the dye. I will spin the engine with the plugs out to hopefully disburse the dye,

This sounds like another fantastic opportunity for you to film yourself doing something entertaining.

Pics or it didn't happen!!    LOL

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1 hour ago, Patcon said:

So what changed?

I wish I knew, only thing I did was add the uv dye to the system. Clearly I will be retesting, I am using the fluid from the same bottle, I should have sniffed from the tail pipe to confirm color change, will do that next time. I will conduct more test over the coming days. Thing is IIRC I had the same thing happen on the N42/MN47 spare engine, failed at 1st then tested fine later and ever since. REALLY bugs me but if I can't get it to fail again (and remember it never overheated when it did indicate fail) then I will take the W, don't want to look a gift horse in the mouth. 

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ah, a variable...

whilie I was putting the engine away for the day I recalled my plan to look in the cylinders (before doing the last chem test that was a win.

My plan had been to inspect for dye in there, in prep for that I had only installed the plugs finger tight to briefly run the engine to circulate the dye.

SO, is it possible that some of the exhaust pressure was leaking past a less the fully tighten plug, thereby reducing the combustion chamber pressure enough to allow for the test to pass? Its at least something to go on. Its too late for me to run the engine now, but will make sure the plugs are torqued to spec an will try again tomorrow. Geez I hope is passes, but if not at least the puzzle will be solved.

And if it does fail I think I will try running while disabling one cylinder at a time (pull the fuel injector connector off). That should allow me to narrow down the issue. I actually started down the path earlier before running it in the video. I had removed #6 plug, thinking it would lessen the load on the engine to not have to compress just the air, well silly me, engine ran like crap, massive air leak I guess, so I reinstalled the plug (hand tight) and the video was made. 

Now to be clear the plugs were not loose, fully seated, and I could not detect any odd noises while running making the video, Just snugged up with to the washer.

 

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