Cylinder compression

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Marc
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Posts: 4
Joined: Sun Apr 08, 2018 7:36 pm
My tercel:: 1986 Tercel 4wd Wagon x2
Location: Langley, BC, Canada

Cylinder compression

Post by Marc » Sun Apr 08, 2018 8:21 pm

Hi all, new to the forums here.
I recently bought two 86 tercel 4wd wagons. One was the previous owners daily until it quit starting on him about 3 months ago. The other is a running parts car. Only paid $600 for the pair.

Anyway, I was working in the old daily today trying to get it to run. It has good spark, airflow and fuel getting to the carb. Timing was perfect. I did a compression test and the worst cylinder was 80psi and the best was 95 psi. Obviously that is really low. My questions are what is the compression of a "new" motor? (I suspect somewhere between 130 and 150psi but I cant find any definitive numbers). They other question is what is the minimum compression needed to just run it? Is 90ish enough that it should run, or is that more than likely the cause of my no start issue.? Im also assuming that with the fairly even compression this would be a ring issue and not a valve or head issue. The car has 450,000 I'm and I'm unaware of any rebuild that's ever been done to it.

I also noticed that while I flooded the carb with fuel, my plugs stayed dry. Could it be a carb problem where no fuel is making it to the chamber? I wet each plug with fuel and it started to sputter a bit but still never started.

Any input on this?

I'm planning to check out the other motor tomorrow.
1986 Tercel 4wd 5 speed sr5, 455k, project car
1986 Tercel 4wd 5 speed sr5, 360k, parts cars
1988 Honda Accord EXI, 96k(!), auto, daily driver
1995 Jeep XJ Country, i6, auto, 355k, 4x4

xirdneh
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My tercel:: 87 tercel 4x4 wagon w/reringed engine, 83 tercel 4x4 wagon w/salvaged engine and 4.1 Diff's
Location: seabeck, washington, USA

Re: Cylinder compression

Post by xirdneh » Mon Apr 09, 2018 8:14 am

I would try a tablespoon of gas poured into carb. If car fires up and dies then the carb is clogged up.
The highest readings i have ever seen is 180.
Love those Tercell 4x4 wagons but they sure suffer from road noise.

Marc
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Posts: 4
Joined: Sun Apr 08, 2018 7:36 pm
My tercel:: 1986 Tercel 4wd Wagon x2
Location: Langley, BC, Canada

Re: Cylinder compression

Post by Marc » Mon Apr 09, 2018 11:00 am

I tried squirting gas into the both the primary and secondary on the carb and it made no difference. The only time it did anything other than crank is when I wetted the plugs. It popped a few times and dried the plugs but didn't start.

I'm also getting a significant amount of blowback through the carb when it's turning over. I'm wondering if the lack of compression in the cylinders is making it so I don't have enough vacuum to get any fuel into the motor? I'm grasping at straws here.
1986 Tercel 4wd 5 speed sr5, 455k, project car
1986 Tercel 4wd 5 speed sr5, 360k, parts cars
1988 Honda Accord EXI, 96k(!), auto, daily driver
1995 Jeep XJ Country, i6, auto, 355k, 4x4

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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Cylinder compression

Post by Petros » Mon Apr 09, 2018 12:52 pm

welcome to the forum.

that engine should still run, but be low on power output. how is your timing belt? when they start to break down sometimes they can skipp a few teeth, making it hard/impossible to start. if that is the case it should be replaced. pull off the front plastic timing belt cover and get a good look at it and verify that the cam timing is correct to the TDC mark on the crank. verify belt tension while you are at it.

have you check for a strong spark? if coil or the igniter in the dist gets weak/bad it could act this way. even with low compression you should get a breif run when you put fuel in it, so sounds like you either have no spark, or the spark is occurring at the wrong time (bad timing belt).

good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

Marc
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Posts: 4
Joined: Sun Apr 08, 2018 7:36 pm
My tercel:: 1986 Tercel 4wd Wagon x2
Location: Langley, BC, Canada

Re: Cylinder compression

Post by Marc » Mon Apr 09, 2018 4:27 pm

Spark is strong and hot. Distributor, plugs and wires are all new. I checked the timing as well. It's set at 5 degrees which is what it says under the hood that it should be. I also checked the distributor was pointing at the right plug at the right time. It's not 180 out or anything like that.

Timing belt is in good shape and is tensioned decently well. Tight enough that it wouldn't skip a tooth anyway.

I really feel like something is preventing fuel getting from the carb into the chamber but I don't know what would cause that.
1986 Tercel 4wd 5 speed sr5, 455k, project car
1986 Tercel 4wd 5 speed sr5, 360k, parts cars
1988 Honda Accord EXI, 96k(!), auto, daily driver
1995 Jeep XJ Country, i6, auto, 355k, 4x4

xirdneh
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Posts: 1978
Joined: Thu Aug 04, 2005 11:38 am
My tercel:: 87 tercel 4x4 wagon w/reringed engine, 83 tercel 4x4 wagon w/salvaged engine and 4.1 Diff's
Location: seabeck, washington, USA

Re: Cylinder compression

Post by xirdneh » Mon Apr 09, 2018 7:12 pm

maybee the car sat with carb throat open and honey bees made a nest in the manifold.
i am just beeing goofy but weird things happen.
Love those Tercell 4x4 wagons but they sure suffer from road noise.

teranfirbt
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My tercel:: '86 SR5 4WD, 5AFE, lifted rear, 195/70/14 tires
Location: Seattle, WA

Re: Cylinder compression

Post by teranfirbt » Mon Apr 09, 2018 8:43 pm

90 is on the lower end of what will run, realistically. Fresh engines are typically in the 170 to 190 range for compression, 130 or so is where you want to start considering a rebuild.

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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Cylinder compression

Post by Petros » Mon Apr 09, 2018 8:49 pm

does it run if you spray starting fluid, or add gasoline, down the carb throat? it should run momentarily and than die. that would indicate no fuel supply. It is does not run briefly, likely spark is off.

BTW, where did you get a "new" distributor? if it is remanufactured, I would suspect it is junk. I have seen three "new" (rebuilt) distributors be bad right out of the box. I would not trust them unless you have ran it in a known good running Tercel to prove it is good.

only two reasons it will not run: no fuel, or no spark. It could also be too much fuel, could have spark at the wrong time. Work back from these basic functions and usually the you can find the problem fairly fast.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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splatterdog
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Location: Minnesota, USA

Re: Cylinder compression

Post by splatterdog » Tue Apr 10, 2018 10:44 am

xirdneh wrote:
Mon Apr 09, 2018 7:12 pm
maybee the car sat with carb throat open and honey bees made a nest in the manifold.
i am just beeing goofy but weird things happen.
Weird but possible! Along that same line of thought would be a mouse nest completely plugging the exhaust.

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TooManyToyota's
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My tercel:: 1984 Tercel 4wd SR5, 1987 tercel 4wd 4a-fe swap
Location: Hudsonville MI
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Re: Cylinder compression

Post by TooManyToyota's » Sun Apr 22, 2018 9:55 am

my car is a 1984 Sr5 with 109,000 miles and I got 140-150 psi in all cylinders on a recent compression test
Cars
1984 Tercel Sr5 4wd 6 speed Red/tan
1987 Tercel Sr5 4wd 6 speed Gold (4a-fe swapped)
1988 Camry Station wagon 5 speed (305k and climbing) (winter rig)
1989 Nissan Pulsar NX 5 speed (autocross rig)
1997 Pontiac Sunfire (Circle track car)
1991 Camry V6 wagon (Derby car)
1987 Celica Convertible 4 speed auto (for sale)

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