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post #1 of 19 (permalink) Old 06-11-2011, 10:00 PM Thread Starter
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Exclamation 94 lt1 problems

Hello all new to this forum diggin it. Just bought a 94 z28 140k 3000$ a week ago seller said all it needed was plugs n wires car was missing at low rpm's and valve chatter at high i checked all the fluids before i drove back all was ok. I drove the car 40 miles back home and soon as i turned into my block the car blew all the antifreeze out the tail pipe . It never overheated stayed right above 160 degrees. Does this sound like a head gasket? withthe radiator cap off my hand over it i could fell air blowing out. Also oil pressure stays at 1/4 way on gauge idle and rev whats up with that?
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post #2 of 19 (permalink) Old 06-12-2011, 08:59 AM
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Antifreeze out the tailpipe is very likely a blown head gasket. Gasket is blown in a place where coolant is getting into the cylinder and going out the exhaust. Blown head gaskets can have a verity of symptoms depending on where the gasket blew out at. Of course theres always the possibility of a cracked head or even the block, but fortunately head gasket is primary suspect.
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post #3 of 19 (permalink) Old 06-12-2011, 11:46 AM
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Could be a faulty oil pressure switch, faulty gauge or just plain old low oil pressure you need a mechanical gauge fitting to make sure whats what.
If there's mechanical chatter at high revs it could be low pressure, hope not as it means pulling the motor and a rebuild.

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post #4 of 19 (permalink) Old 06-13-2011, 09:43 PM Thread Starter
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so a blown head gasket cant cause low oil pressure?
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post #5 of 19 (permalink) Old 06-14-2011, 06:05 AM
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Blown head gasket usually doesn't lower oil pressure. Bad crank bearings are the number 1 reason for low oil pressure. But before you get in a twist over the oil pressure, get a mechanical oil pressure guage and attach it and run engine to verify pressure is actually low. Many times the oil pressure sender goes bad. If your pressure gets higher when you rev the engine I would bet on a bad sender. But you still have the head gasket problem to tackle.
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post #6 of 19 (permalink) Old 06-14-2011, 06:59 PM Thread Starter
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A little update i took off the valve cover on the drivers side started the car i have no oil coming out of the pushrods. My guess oil pickup tube fell off??

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post #7 of 19 (permalink) Old 06-14-2011, 09:45 PM
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Before you pull the oil pan off , go and remove the oil pressure sender from the engine block. On 94 its right above oil filter. If not there there will be a plug in its place. Remove the sender or plug if its there and have assistant start car for just long enough to see if theres flow from the hole. If no flow, your idea of pick up tube being off could be true, or it could be the plastic clip that holds the oil pump drive to the oil pump broke. If you get oil flow from the hole then pump is working and you have blockage elsewhere. Go to www.shbox.com go into the component view category and click on # 25 aux oil fitting, it will have a good view of the plug found in 95 and newer models, your oil pressure sender should be there, unless a previous owner updated the car.

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post #8 of 19 (permalink) Old 06-15-2011, 06:59 AM
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I forgot to tell you if your getting enough coolant in the cylinder to make its way out the tail pipe in the quanity you describe, theres a serious chance of hydrolocking your engine if you continue to run it. Go ahead and do the oil pressure test from my last post, if you have and oil pressure test guage use it instead of leaving the oil press sender or plug out, but only run your engine long enough to check to see if oil pump is putting out pressure. When you hydrolock an engine you can bend or break connecting rods and other parts. So fix the coolant problem as well as your oiling problem before it gets even worse and you need a whole new engine.
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post #9 of 19 (permalink) Old 06-17-2011, 08:07 PM Thread Starter
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I found that taper plug right above the filter removed and ran engine for 10 sec there is oil coming out but not at a fast rate. So than i drained the oil it looked like chocolate milkshake. Tapped the pan with a hammer no rattling so i guess that cancels out the pickup tube falling off. Is the water in my oil causing the constant low oil pressure and no flow threw the pushrods?

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post #10 of 19 (permalink) Old 06-17-2011, 08:14 PM Thread Starter
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oil never drops to 0 just stays really low 10 idle maybe 15 driving.
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post #11 of 19 (permalink) Old 06-17-2011, 08:57 PM
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If you got water in the oil you need to stop running the car. It can eat you bearings up and make a bad situation worse. Your oil pump is working so you need to fix your blown head gasket before you need much more repair. Have your heads checked by the machine shop for flatness and cracks so you won't be putting a bad head back on the car and starting your problems all over again. Drain the oil and change the filter, like yesterday, and drain enough coolant out of the system so the water level is no higher then the engine block. This will keep more water from going into the oil while you wait to repair . Once you replace headgasket, run engine for a few minutes and replace oil and filter again. When I have the water in oil problem, I take the oil pan off, remove the oil pump. Then I clean everything I can get to and put it back together. But most people don't want to go to that much trouble. They just change the oil several times and its ok.
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post #12 of 19 (permalink) Old 06-18-2011, 04:58 PM Thread Starter
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Quote:
Originally Posted by cocobolo95 View Post
If you got water in the oil you need to stop running the car. It can eat you bearings up and make a bad situation worse. Your oil pump is working so you need to fix your blown head gasket before you need much more repair. Have your heads checked by the machine shop for flatness and cracks so you won't be putting a bad head back on the car and starting your problems all over again. Drain the oil and change the filter, like yesterday, and drain enough coolant out of the system so the water level is no higher then the engine block. This will keep more water from going into the oil while you wait to repair . Once you replace headgasket, run engine for a few minutes and replace oil and filter again. When I have the water in oil problem, I take the oil pan off, remove the oil pump. Then I clean everything I can get to and put it back together. But most people don't want to go to that much trouble. They just change the oil several times and its ok.
Went to my local autozone today bought a manual pressure tester new filter and 5 quarts of oil 10w-40. took off the old oil filter and cut it open creamy watery oil caked in the filter. put in the new oil changed the filter hooked up the manual tester where that taper plug is fired er up 12 psi on the guage still bad.. So back to the oil pickup tube, screen it's probably clogged gummed up. Whats the best way to backflush the oil pump? Hateto pull this dam motor want to troubleshoot everything first before I tackle the headgasket.
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post #13 of 19 (permalink) Old 06-18-2011, 05:55 PM
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Really no way of doing a good flush. You need to drop the oil pan which involves unbolting the motor mounts and jacking engine up enough to remove oil pan. But even though you should remove the pan and oil pump and clean everything, don't run the engine anymore until you fix the head gasket. If you don't run it anymore and fix the problem, theres a good chance your bearings will be ok. While you have the pan off you can remove a couple of main bearing caps , one at a time to check the main bearings, and remove a couple of rod caps to check their bearings.

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post #14 of 19 (permalink) Old 07-02-2011, 08:54 PM Thread Starter
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Well i found all the problems, Both head gasket's blown and broken sender. I checked the heads they look in good shape but im still going to give them to the machine shop to check for cracks and warpage. If all is good im only having them milled. I got parts in the mail comming proform 1.5 RR,proform pushrods,sealed power lifters, felpro head gasket set, all together came out to 700$ in parts ?$ to mill both heads. Heres some pics of gaskets each blew out in the same spot cylinders #7 #8. Also turned the motor over with the heads off by hand moves smoothly no bindage crank and rods should be fine. I think this engine is salvageable after all..

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post #15 of 19 (permalink) Old 07-03-2011, 08:37 AM Thread Starter
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Took the oil tester out before i torn down the motor noticed i didnt have the tube in the brass fitting all the way the brass ferrule pinched the bottom of the tube. these pics were takin at the same time.

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