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1994 plymouth acclaim v6. ok so what brought me to this was an overpressurized coolant system. i replaced the thermostat and overflow cap, as well as all the hoses and clamps… started the car yesterday, and noticed an excess of white smoke from my exhaust pipe…not a crazy lot though, enough to where i cant tell if its just a little oil from my valves (thats been going on for years) or antifreeze. i cant pinpoint the smell either.
when i put fresh coolant in and let it run i noticed bubbles coming out of the resivoir, but it went away after 10 minutes…thats when the smoke started happening.
so i pulled all the spark plugs out today and checked em, they all seem perfectly fine… nice dry consistent… only my number 5 rear drivers side plug had a little bit of wetness on only the threads, but it seemed to be oil rather than antifreeze.
now i did a compression test on all of my cylinders about 7 months ago so i have those readings to go off of…and i just tested the cylinder that had the dampness on the plug threads, and it read about 142 psi, that compared to the 161 psi i had on it 7 months ago. also this was done while the engine was warm, not hot but warm.
so is it possible for a minor gasket leak to only read a 20 psi decline in pressure or is this just due to normal engine wear or some other factor? if its a minor head gasket leak im obviously going to change it anyways, but its so minor that i’m just having trouble pinpointing any symptoms eg: milky oil, oily antifreeze ect.
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After reading this post I highly doubt it’s a head gasket. Have you pressure tested the cooling system? have you drained the oil and inspected that?
[quote=”Chuzzlepuff” post=169601]when i put fresh coolant in and let it run i noticed bubbles coming out of the reservoir, but it went away after 10 minutes…thats when the smoke started happening. [/quote]
That would be air in the cooling system bleeding.
[quote=”Chuzzlepuff” post=169601]
now i did a compression test on all of my cylinders about 7 months ago so i have those readings to go off of…and i just tested the cylinder that had the dampness on the plug threads, and it read about 142 psi, that compared to the 161 psi i had on it 7 months ago. also this was done while the engine was warm, not hot but warm.
[/quote]What were the compressions on all of the cylinders?
Did you have a bad catalyst? In these Maxima’s the pre cat is failing not allowing sufficient exhaust to breath and the engine deteriorates.
You may have to pull that head to have a look, which means a gasket change anyway. If the valves and combustion chamber in the suspect cylinder look clean, while the other chambers show carbon and dark fuel deposits, it’s evidence of coolant getting into the cylinder and steam cleaning it.
With the head off, you can also check the head and deck surfaces for irregularities that would cause poor gasket sealing. And the gasket itself might show signs of erosion from a coolant passage leaking into the cylinder.
Before you tear things down, do a wet compression test to see if it has any effect on the readings.
Also, with the right equipment, you can plumb compressed air into the cylinder’s spark plug hole at TDC with the valves closed. If you hear air escaping into the exhaust or intake, it points to poor valve seating. If air bubbles into the cooling system, it indicates a head gasket issue. And the sound of air escaping into the sump and heard at the valve cover oil filler hole and open dipstick tube indicates poor ring sealing.
it won’t make a difference if it’s repaired, if the Cat is bad it’s going to damage the new repairs.
If the compression is low the engine needs to be replaced right?
You could get a replacement for that one for under $500.
What caused the BHG in the first place?
ok update guys, thanks for the input by the way! sorry defcon, but i managed to check the compression on all the cylinders today. i did this cold, because i did it cold when i did the control compression test 7 months ago.
results: my cylinders are numbered passenger to driver side 1 3 5 in the rear and 2 4 6 in the front…
7 months ago pressures: 1. 159 2. 158 3. 158 4. 145 5. 161 6. 150
Just now tested pressure: 1. 151 2. 160 3. 151 4. 160 5. 152 6. 160
so as you can see, nothing is astonishingly low… some of the cylinders have decreased in pressure by 10ish lbs, but then on the flipside some of them have increased by like 10 psi from last time.
on a side note, the 5th cylinder i was talking about in the original post last night read 142 then…but i did it today with the engine de-warmed and it read 152, i guess that descrapancy seems normal considering temperature expansion and such?
should i do a compression test with the engine hot to get reliable results or is this sufficient? logically things expand when heated so if there were any leak it would be most apparent with the engine cold i assume?
Evil, back to you, obviously i dont want to take the head off unless its completely necessary (i may not be as much of a masochist as you) lol but i can definitively say that all of the spark plugs looked exactly the same, the whole end of it, (atleast the part exposed to the cylinders) looked pristene and healthy…that bit of oil or whatever on the threads i’m thinking may have come from outside the engine, like a little oil soak from some other little leak?
also the compression hose i have has a nice little air compression male fitting on the end, so i think what ill do is hook it up to my little air compressor for each cylinder and check for bubbles as per TDC. so if that checks out and you guys agree the pressures i got and spark plug conditions are pointing away from a head gasket problem, i think what ill do is just drive the car around… i figure if it is a tiny head gasket leak…in no time it will get worse and become very apparent. phew i hope it all works out
here is some video of what chris fix did looking at head gaskets one of them is blowen and this is what evil was saying looks like its steamed clean… that would tell you iff you have a blown head in the past… but didnt you already replace it???
this might hlep you out a little bit
How To Perform a Compression Test – EricTheCarGuyno i didnt yet. i’m trying to diagnose if its actually blown before i…you know…tear apart half my engine lol
here is more fancier and some berret ways to check it
here is scannerdanneranother way is oil analysis
thats some of the other ways you can check but are a little bit more advance… but sometime I will like to do an oil analysis on my car and have them check it out.. the camera that chris fix uses is like $20 but of coarse you will have to wait until it comes it.. but unless you think you have a head leak I would try the car out and keep a very close eye on it and see what happens
awesome. everything checks out so i’m gonna use it for a couple days and see if anything goes south. also i had no idea you could tell so much about your car from just the oil though thats so cool! i’m totally getting a kit soon, for 28 bucks hell yeah.
[quote=”Chuzzlepuff” post=169760]awesome. everything checks out so i’m gonna use it for a couple days and see if anything goes south. also i had no idea you could tell so much about your car from just the oil though thats so cool! i’m totally getting a kit soon, for 28 bucks hell yeah.[/quote]
let me know what you think about the kit…. Im going to have to wait untill I do an other oil change 🙁I dont know how long you have waited untill you have done your last oil change also when you do it… you can check if there is antifreeze in the oil… by when you drain it put it all in a clear bottle or 2 and put in on the shelf to sit … remember oil and water dont mix 🙂 so it will ceperate but you cant shake it or touch it for like 2-3 days
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