350 Head Gasket Replacement

Old October 20th, 2017, 06:25 PM
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350 Head Gasket Replacement

Hello everyone, I'm new here and wanted to get some advice on how to replace head gaskets on my 71 Olds 350. I don't know much about this engine because i recently bought the car and I don't have much mechanical experience but I'm ready to start getting my hands dirty. The engine does have an after market manifold-Edelbrock RPM Performer. So, I'm still gonna do a couple of test to try to be sure if it is a head gasket problem. Let me tell you what's been happening. I drive the car for 15-20 minutes somewhere, shut it off, and try to start it again and it doesn't wanna start, once it cools it will come back to life(I try to start it some many times I need to jump it after for it to start). The other day i saw a light white smoke coming out of my left tail pipe when i press the pedal down right as I start the car. I put my hand over the left exhaust pipe and i felt moisture, the right tail pipe felt dry and normal. When i started the engine 20 minutes later I felt a light smoke comes out of the space between the block and head on the left side where the gasket is and also smoke coming out of the right side through the oil breather cap(the cap that goes in the right head). The car has always ran a bit rough during idle when i start it up, but now it just seems a bit worse. I just did a radiator flush a month ago and filled the system back up because of the overheating problem, but it didnt solve the problem.

So if you guys could tell me that tools I need to test for a failed gasket and once I confirm its bad, how I can go about changing the gaskets. Thanks guys! .
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Old October 21st, 2017, 06:28 AM
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The starting may be a different problem, sounds like you need to start with a tune-up and a compression test, check the plugs, fluids etc. etc. If you don,t know much about cars or want to invest in tools I would take to old sckool muscle car shop. Other option is to use google and start getting dirty and get some tools if you are going to get into this. Over heating can be bad a thermostat, radiator, or water pump, tune up, head gasket, cracked head or even engine block. To help confirm head gasket pull plugs and look for really clean ones, compression test could confirm finding, then you can also do a cylinder leakage test.
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Old October 21st, 2017, 07:32 AM
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Originally Posted by Christopher Michael Drew View Post
Hello everyone, I'm new here and wanted to get some advice on how to replace head gaskets on my 71 Olds 350.
I would do a bit more trouble shooting before doing a head gasket. As you stated below.

I don't know much about this engine because i recently bought the car and I don't have much mechanical experience but I'm ready to start getting my hands dirty.
A worthy endeavor as restoring through your wallet can get very expensive.

The engine does have an after market manifold-Edelbrock RPM Performer. So, I'm still gonna do a couple of test to try to be sure if it is a head gasket problem. Let me tell you what's been happening. I drive the car for 15-20 minutes somewhere, shut it off, and try to start it again and it doesn't wanna start, once it cools it will come back to life(I try to start it some many times I need to jump it after for it to start).
Does the engine crank and not start or not crank. If the engine cranks and not start then it could be a number of things, a stuck choke, poor tune,
and/or ignition parts need to be replaced.


The other day i saw a light white smoke coming out of my left tail pipe when i press the pedal down right as I start the car. I put my hand over the left exhaust pipe and i felt moisture, the right tail pipe felt dry and normal.
There is a heat riser that stays closed in the exhaust manifold until the engine warms. It works similar to your choke, as the car slowly warms the flap opens. The condensation is normal.

When i started the engine 20 minutes later I felt a light smoke comes out of the space between the block and head on the left side where the gasket is and also smoke coming out of the right side through the oil breather cap(the cap that goes in the right head).
The smoke can be a leaking valve cover gasket or manifold gasket (usually accompanied by exhaust noise). The smoke coming from the breather may be due to blowby, faulty PCV, and/or crud under the valve cover.

The car has always ran a bit rough during idle when i start it up, but now it just seems a bit worse. I just did a radiator flush a month ago and filled the system back up because of the overheating problem, but it didnt solve the problem.
It may be getting worse because your tune is getting worse. You need to tell us more info about the overheating. Is the idiot light coming or what temp your engine is reaching both at idle and while driving. As stated above,
it could be a sticking thermostat, a bad fan clutch, or a blocked up radiator (yes even though you flushed it). It could also be attributed to your state of tune.


So if you guys could tell me that tools I need to test for a failed gasket and once I confirm its bad, how I can go about changing the gaskets. Thanks guys! .
As stated above, a compression check is very useful in determining a bad head gasket. I'll also ad that if your timing chain has not been replaced it could be that also. Tools you'll need:
Basic set of hand tools
Compression gauge
Vacuum gauge
Tach and dwell meter
Timing light (I prefer one thats adjustable)
Feeler gauge
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Old October 21st, 2017, 07:57 AM
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What did the coolant look like? I had replace head gaskets on a 76 350 due to very rusty coolant. The shim head gaskets had actually corroded away around the water jackets. Rent a coolant pressure tester, if you lose pressure, you have an issue. The smoke out of the breather is normal on a tired motor.
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Old October 21st, 2017, 08:48 AM
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The coolant was very brown and had debris in it when I emptied the radiator, the thermostat i assume is fine because the upper and lower radiator hoses has coolant flowing through them. I took off the radiator hoses and they had some dirty inner walls but nothing that could block the flow of coolant.

The engine does try to crank over after these rides until I have to jump it after 10 tries of getting the car started. i go out in the morning or whenever it sits over night or a couple hours it will start right up no problem. The temp light does not come on in my car and i'm in the middle of restoring the car and doesnt have a temp gauge. My radiator is old, not sure when a previous owner replaced it. btw, my 71 Olds Engine is in my Buick Skylark if it makes any difference.

I want to start restoring cars and im already good at interiors and im picking up on electrical and now its time to start with mechanical. So im willing to buy tools, I have a lot already.

When you guys say tune up, what exactly should i have replaced? I have a new fuel system, from gas tank to a new edelbrock carb ( ive been meaning to replace spark plugs, any brand recommendation? I was gonna go NGK. http://www.autozone.com/external-eng...lug/924167_0_0)

Thanks guys for the replies, let me know if i missed a question or throw more at me.
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Old October 21st, 2017, 11:23 AM
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Those are a good plug and my personal favorite. Many have issues with the Edelbrock carb and probably too rich for your 350. The no start when hot is a defect with those AFB(Edelbrock) carbs. Try a 1" phonelic spacer under it to help with the fuel boiling in the bowl. Today's ethanol fuel compounds the problem.

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Old October 21st, 2017, 11:34 AM
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+1 on carb tune, pull those plugs asap, I have an olds 350 in a 76 skylark so welcome to the party!!
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Old October 21st, 2017, 03:20 PM
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Tuneup is points, condenser, cap, rotor, plugs, and wires if they are old and worn. Set dwell, timing, and carb idle air/fuel mixture and ensure the choke is operating properly. Once you get that done, see if it starts correctly. When you try to start the car cold, pump the gas pedal once to set the choke. When its hot, try just turning the key, then while cranking push the pedal 1/2 way and hold it there. Don't keep pumping the gas pedal because it will flood and wet spark plugs won't fire.
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Old October 21st, 2017, 08:55 PM
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How can i tune the carb? any videos someone can show me?

I have some videos of the engine running to show you guys the rough idle and the smoke and the starting problem(the car has sat for a week without driving it so I had to jump it).

Watch Video
Heres the car after i jumped it( it was sitting for a week-week and a half and it was a bit low. You can see a light smoke coming out, I could'nt see where it came from exactly but it might be from the headers. This video is a minute of running the car for the first time today.

This next video is the car running for about 10 minutes, you can see the smoke more in this video. when i press the pedal down i do see smoke coming out of the exhaust.
Watch Video


and finally I shut the car off and try to start it again and this is what I get, now it could be because the battery was low(3 month old battery) but it measured at 12.6V after i tried to start the car again, but even when my battery is charged good, the car does this same thing after those 20 minutes rides when i turn it off and try to start it again.
Watch Video

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Old October 21st, 2017, 09:47 PM
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I also have another question off topic, when i took off my aftermarket gauges for the oil/temp/volt I cut these wires/piping off.

The copper pipe went to the oil pressure gauge and it sends actual oil to the gauge for the gauge to read the pressure?
and the other wire with the coils around it went to the thermostat gauge to give the temp reading. Anyway my question is when i replace these gauges will these two parts be included in most kits or do i have to replace these what would you call them? Oil and temperature sending units?

and is that the PCV valve above the temp wire?

Last edited by Christopher Michael Drew; October 21st, 2017 at 09:49 PM. Reason: wanting to add more
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Old October 22nd, 2017, 12:38 AM
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Video show an exhaust leak and possibly oil leaking onto manifold, starting problem might be bad starter, battery, wiring, charging system. Those sending units for the will come with new gauges and those gauges are very important in an old ride! Old cars need extra love and attention, what I like to do is check all the systems so I understand the health of the car as a whole, make a list. Really should try to find a good old honest shop and find out the health of the car as a whole, set up a base line, get it running better. Explain to them you want to learn and begin working on the car for yourself. Another idea is to hook up with classic car clubs in your area or car shows and maybe find someone to let a hand. The folks on the forums will help as much as possible, buts its hard to explain all this stuff though the keyboard.
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Old October 22nd, 2017, 07:07 AM
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All the smoke is from a valve cover gasket leak.

12.6v is a fully charged battery, I would check/clean for corroded battery cables/connections and/or bad grounds to start with. Pull off both cables from the battery and clean the surfaces where the cables and battery terminals connect to each other. Check/clean the connections at the horn relay and also the 3 wire connections at the starter.

Your engine runs like crap, probably needs a good tuneup. I do hear some valve train noise. I'd ask what your oil pressure is but you cut the tube to the gauge.

Why did you cut all your gauge sensing tubes? The oil gauge works off of actual oil pressure, the temp gauge works of pressure created by temp similar to a thermometer, the volts gauge is connected to keyed power. You can buy a replacement oil tube but the temp gauge will need to be replaced.
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Old October 22nd, 2017, 07:51 AM
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Okay let me explain more history on the car. I bought this is March of this year. It sat for 8 months and I took it to a local muscle car shop to have it freshened up and get it started again. So i got a new gas tank, sending unit, fuel pump, fuel lines, edelbrock carb, battery, alternator, steering column key lock, starter, air filter, and a negative battery terminal. He got it running within an hour but kept it for a week to do the repairs i just listed. The mechanic said it was a good engine and it "ran like a bear" but i had carbon buildup so i should drive it to clear it out. He did say the car did need a lot of work...but he was talking big picture(body work, electrical, interior, etc) He said also the electrical is pretty bad. I want to buy a new wiring harness for the car, but i would need someone to help me. See I cant go back to him because he up charges everything, If i bought the parts and not him(he had a policy he can only buy the parts) it would of been half the price! and i dont like that. Plus I want to do the work now myself, im a type of guy to do things myself and i catch onto things quick.

Okay so ill take the valve covers off and see what I can find. I took the gauges off because they were garbage, since I had the car they never worked, plus i didnt like the location the previous owner out them. and i want to start fresh, the last guy who had this car has just done some back yard mechanic stuff I dont trust it.
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Old October 22nd, 2017, 07:57 AM
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I'd start with replacing the gauges and valve cover gaskets. Once you have the valve covers off post some pictures of what it looks like under there. The problem you have is you don't know what your looking for yet as far as diagnosing issues. You need a friend that has good mechanical abilities to work with and teach you. What makes you think the harness needs replacing?
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Old October 22nd, 2017, 04:20 PM
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Ive been reaching out to all the restoration shops around me to become an apprentice(told them i would clean, work for free, etc) but unfortunately no luck yet..but im searching for some cool car guys I can meetup with and wrench. The wiring has a lot of splices in them, it seems like the car was "restored" twice and they just kept splicing wires. Also none of my gauges on my dash(original gauges) are very accurate, my speedometer gauge needle bounces around, it never sits on a number steady. The Fuel gauge works sometimes, lately it has been better. The aftermarket RPM gauge is just out of whack, its just widely inaccurate,the needle just goes crazy. and you already know my issue with those aftermarket temp/oil/volt gauges that are now out of the car. Like I said before the guy who had the car before me didnt know what he was doing and i want to restore this car completely so if i wanted to drive the car across the country with no issues, I could.
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Old October 22nd, 2017, 04:44 PM
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Disconnect the tach if it's wonky. Get a new set of gauges because you need a way to monitor those items. Where do you live? Is there an Olds Club chapter in your area?
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Old October 22nd, 2017, 05:09 PM
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Yeah i want to get some Autometer american muscle gauges very soon. I'm not sure how to find those clubs, and my car is a buick skylark with an olds engine so im kinda wondering which club to go haha and i live in south florida
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Old October 22nd, 2017, 05:19 PM
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Google Oldsmobile clubs in Florida
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Old October 24th, 2017, 04:58 PM
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I just pulled the old spark plugs(no clue how old they are but what you can tell from the pictures the spark plugs have the paint from when the engine was painted by a previous owner, what jumps out at me is the burnt like tips, and the dirt on the second one in on the right head). Take a look at the picture and maybe you guys can tell me about the plugs. Also when I was taking off the spark plug wires, the metal ring that caps onto the spark plug came off, it doesnt look damaged, can i just stick it back down there?
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Old October 24th, 2017, 05:17 PM
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Those look pretty bad, the ones that look wet, look oil fouled. Next step compression test. 3 look pretty good, and some look carbon fouled. The ignition system needs a full tune up and the charging system checked, you might just have a crap battery. Compression test would be my next move. New plugs wire and cap, coil test, verify the charging system is working and get a new battery if its really old.
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Old October 24th, 2017, 05:44 PM
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Can you recommend an affordable compression tester?
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Old October 24th, 2017, 08:39 PM
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No you can't stick the plug terminal back in, it won't make proper contact with the carbon wire. Time for new spark plug wires as well as plugs and points.
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Old October 25th, 2017, 12:49 AM
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Originally Posted by Christopher Michael Drew View Post
Can you recommend an affordable compression tester?
Cheapest route is to borrow one from an Auto store for free or harbor freight tools for cheap stuff thats ok. Large vacuum gauge is a great tool to have around also.
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Old October 25th, 2017, 07:53 AM
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I'm going to search for the most accurate compression tester today, but how do i exactly do a compression check?
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Old October 25th, 2017, 12:38 PM
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Google it, Eric the car guy has good videos on you tube
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Old October 25th, 2017, 01:25 PM
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Any inexpensive compression gauge will probably be fine, I prefer the screw in type. Those plugs look horrible in the pics above. You need to perform a major tuneup and replace all the wear parts.
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Old October 25th, 2017, 05:19 PM
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I don't think the plugs represent the engine currently, but i might be wrong. The plugs for whatever reason weren't changed by the muscle car shop i brought the car to get it running. So i don't know how long those have been in there...I just need the engine to last a couple more years until i get a 455bb. I bought new plugs and after the compression check, ill install them and i will check them after a month and see how they look.
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Old October 25th, 2017, 06:40 PM
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You also need to change the points, condenser, plug wires, cap, and rotor. In addition you'll need to set dwell/timing, carb air/fuel mixture and idle speeds.
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Old October 25th, 2017, 07:43 PM
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I don't have the knowledge to do that right now, but ill look up some products and how to videos and see what tools ill need.
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Old October 26th, 2017, 02:40 PM
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Okay, the results are in for the compression test. I rented a compression tester from autozone. My results were weird..
Cylinder 1:First Attempt: 150 Second Attempt:140
Cylinder 2:First Attempt: 90 Second Attempt: 90
Cylinder 3:First Attempt: 90 Second Attempt: 90
Cylinder 4:First Attempt:120 Second Attempt: 120
Cylinder 5:First Attempt: 150 Second Attempt: 150
Cylinder 6:First Attempt: 150 Second Attempt: 150
Cylinder 7:First Attempt: 150 Second Attempt: 145
Cylinder 8 First Attempt: 150 Second Attempt: 150

So after seeing such different compression rates, I decided to check out the reviews for this gauge on autozone.com. over 30 reviews say this compression tester doesnt go over 90psi, but mine did, but really it only gave me two number 90 or 150, and the 120. Is it uncommon to get a few cylinders right on the same number? What do you guys think of the results? is 150 where i should be at?
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Old October 27th, 2017, 05:21 AM
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The tester should read 0-300 psi. A sound engine should have at least 100psi with no more than 15 psi variation between cylinders. 130 psi is ok ,150 psi on an olds cylinder is good, 150-200 is very good. The 2 cylinders with 90 are not good and you need to investigate them. Oil in cylinder test, leak down test. Go to Eric the car guy he will teach you these methods.
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Old October 27th, 2017, 08:29 AM
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Yes, the tester does read 0-300psi. I did notice removing the tester from the spark plug hole that there was oil on the threads. I forgot which cylinders exactly, Ill have to check again. I already watched eric the car guys video on leak down test a couple of days ago. I'm gonna have to borrow a compressor or go somewhere with air.
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Old November 2nd, 2017, 04:56 PM
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Okay i just did my leakage test. I only did the bad cylinders (2,3,4 with the compression numbers above). So cylinder 3 was reading between 30-35% leakage, cylinder 2 and 4 was reading 15-20% leakage. I couldn't hear or feel any air escaping though oil, carb, or exhaust pipe and no bubbles when i looked in the radiator. I'm pretty sure i was at top dead center. So what does this mean?
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Old November 3rd, 2017, 05:18 PM
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It could be a little of all, engine is just beat. It could be escaping through the valve seats and guides, pull the pvc and breather to listen. Just get hotter plugs and run the **** out of it till you get that 455.
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Old November 3rd, 2017, 05:45 PM
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Yeah i didnt check the pcv but i checked the breather and nothing. Yeah I would love to drive the crap out of it if it would let me lol but this overheating situation is a nightmare.
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