307 olds excessive blow by

88' Cadday

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I opened the engine oil filler in my Cadillac brougham while the car running and there is an excessive blow by coming from the engine. I also checked the lvl of the engine oil and it showed low, so I added half litter. The car was only driven 670 miles after I did an oil change last month.

Another thing is that you step on the gas from a dead stop, the tailpipe emits white smoke.

Any suggestion or advice?
 

Rocketman269V

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Feb 26, 2020
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Do a compression test and a leak down. You didn't mention how it's running: dead miss, stumbling, rough idle. Sounds like possibly worn/stuck oil rings or broken ring lands on the pistons. Was/is the engine "pinging" on acceleration?
 
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Olds 307 and 403

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The best stuff for freeing stuck rings is Kleenflo Combustion Chamber Cleaner. I would run till it stalled and then sprayed in the spark plugs holes and let sit overnight. I got burnt, after multiple motors doing the treatment. I hydro locked #7 and bent a connecting rod and wasted the bearing, still gained back 15 psi, 25 psi on #8 without a bent rod. As said a compression and leak down test along with an oil pressure check will tell a lot. It may just be tired.
 
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88' Cadday

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How to check the oil pressure. I am also wondering if seafoam would help as a cleaning agent. Also if anyone recommends gauges to monitor the oil pressure, water temp, etc
 

Olds 307 and 403

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Nearly any basic triple gauge set with a braided oil line to replace the plastic tubing with give the oil pressure numbers you need. The access is the port to the right of the oil fill tube above and behind the water pump where the casting numbers are located.
 
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88' Cadday

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The best stuff for freeing stuck rings is Kleenflo Combustion Chamber Cleaner. I would run till it stalled and then sprayed in the spark plugs holes and let sit overnight. I got burnt, after multiple motors doing the treatment. I hydro locked #7 and bent a connecting rod and wasted the bearing, still gained back 15 psi, 25 psi on #8 without a bent rod. As said a compression and leak down test along with an oil pressure check will tell a lot. It may just be tired.
I have check engine lights with codes #21, #34, and #43. I am not sure if it has any impact on the symptoms the car has?
 

IndySX

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I ordered an 86 Cutlass with a 307. It wasn’t long after the warranty expired I noticed a blow by issue. As I worked to get issue addressed from Oldsmobile I was informed that the alloy in a fair amount of 307s was soft which caused this problem. They put a re-man in it. Man I loved that car. Hope you get it.
 

Olds 307 and 403

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Isn't that around the time motor production moved to Mexico? I believe there was cracking issue with 87 307 blocks. We actually had a couple in our College Auto Tech program.
 

IndySX

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I have never heard that one before. Probably because I’m a Olds nut but not one who works on them. I was lucky enough to buy that 86 new, had a 71 along side it. I look at them everyday. My hope is someday to have a 70-71 W-30 before they are out of reach. A 75 Hurst would be nice also.
 

88' Cadday

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Another thing worths mentioning is that I noticed that the lvl of coolant is low although I have top it off couple of weeks ago but it takes some times to go low as I am watching the overflow tank
 

Intragration

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I have Autometer electric gauges on all my cars. I was for some reason never a fan of having an oil line coming into the car, and find routing of wires a lot easier than a nylon line.
 

Rocketman269V

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I'm not a fan of tiny nylon oil lines at all. I have installed numerous mechanical oil pressure gauges in my vehicles, as well as in customer cars. I always use a 1/4" braided stainless steel hose for safety and for a more responsive gauge. On my race car, I used a 3/8" line, which is really responsive.
 

Olds 307 and 403

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I also use the braided lines for my oil pressure gauge. I had one fail but at 4 feet it was barely enough. I have ran the 5 and 6 ft ones with no issues.
 

88' Cadday

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I opened the engine oil filler in my Cadillac brougham while the car running and there is an excessive blow by coming from the engine. I also checked the lvl of the engine oil and it showed low, so I added half litter. The car was only driven 670 miles after I did an oil change last month.

Another thing is that you step on the gas from a dead stop, the tailpipe emits white smoke.

Any suggestion or advice?
I checked again the engine oil lvl and found that low by one litre. The car now was driven 810 miles. So it is only 140 miles after the previous top up.

I need your advice. The car drives very smoothly but I don't know what is really happening. Could it be a piston ring? I don't know
 

Olds 307 and 403

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Melville, Saskatchewan
It sounds like an Olds 350 or 403 swap should be considered. It could be valve seals and or worn rings. A compression test and hooking up an oil pressure gauge will tell a lot.
 
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88' Cadday

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It sounds like an Olds 350 or 403 swap should be considered. It could be valve seals and or worn rings. A compression test and hooking up an oil pressure gauge will tell a lot.
I just bought gauges for oil pressure, w
16052904408338594194323582816168.jpg
 

88' Cadday

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Water temp and volt. I haven't decided yet where should I put but I think under the ashtray would be feasible
 

Rocketman269V

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I've always wondered why they changed the range on water temperature gauges, so that 230 is now at the top and the gauge goes up to 280! The gauges that I remember "back in the day" had a high reading of 230 and the normal range (160-180) was at the top. Now the useable range is all squashed together on the low side. :mad:
 

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