Birdcage of Doom...

[Asterix]

So, I head out to run some errands and 4 miles from my house, my birdcage lights up. I quickly find a place to turn and stop, easily under a minute from when I saw the warning light. After a tow home and some inspecting, I find that the heater valve body is broken on the engine side. I lost maybe half my coolant. I figure everything's ok, since I caught it fast and it was maybe 40F outside.

After putting a "new" heater valve and refilling the coolant, the engine starts just fine and runs as ok as it ever does cold. But it never seemed to warm up or run right. It idled smoothly, but stumbled when I revved it.

The thermostat and water pump are both fine. Surely there was air in the system, which I'll try harder to get rid of when I refill it.

Since there was already no coolant in there, I ran a compression test this morning. 5 of the 6 have 210-215psi, but #2 tops out at 190psi.

The book says there should be under 15psi difference between cylinders, but it also says the typical pressure is only 156psi.

Any opinions on if I should tear the engine apart (again)? The engine has under 10,000 miles on it after a major overhaul. That's what annoys me the most.

Asterix

 

[Setheroo]

Just sounds like bad luck - I don't think that your compression readings are bad.

If I were you I would work on getting the air out of the system first to be able to see what is really going on.

 

[sbenson619]

So, I head out to run some errands and 4 miles from my house, my birdcage lights up. I quickly find a place to turn and stop, easily under a minute from when I saw the warning light. After a tow home and some inspecting, I find that the heater valve body is broken on the engine side. I lost maybe half my coolant. I figure everything's ok, since I caught it fast and it was maybe 40F outside.

After putting a "new" heater valve and refilling the coolant, the engine starts just fine and runs as ok as it ever does cold. But it never seemed to warm up or run right. It idled smoothly, but stumbled when I revved it.

The thermostat and water pump are both fine. Surely there was air in the system, which I'll try harder to get rid of when I refill it.

Since there was already no coolant in there, I ran a compression test this morning. 5 of the 6 have 210-215psi, but #2 tops out at 190psi.

The book says there should be under 15psi difference between cylinders, but it also says the typical pressure is only 156psi.

Any opinions on if I should tear the engine apart (again)? The engine has under 10,000 miles on it after a major overhaul. That's what annoys me the most.

Asterix

try putting a little bit of oil in #2 and see if the compression goes up

 

[AJ'S 88NA]

That much compression may mean too much carbon build up. On a fresh motor with 10.5-1 pistons I had 190lbs.

 

[Asterix]

sbenson619, I tried that, but probably didn't put in enough oil for it to make a difference. I'll put more in and check again.

AJ'S 88NA, how can that much carbon build up in only 10,000 miles? Now, when my engine was rebuilt, the shop shaved 0.030" off the head, which is a lot. I calculated my compression ratio at about 9.2:1. It couldn't be higher and not ping badly on mid-grade gas. I thought 215psi was a lot, but it didn't seem out of line for a fairly fresh engine.

After I recheck the compression on #2 with a bit more oil, I'll just put it all back together again, refilling the coolant better to get rid of the air and run it a while until the thermostat is definitely open. If it runs fine, I'll just recheck the compression in 5,000 miles or so and see where it is then.

Asterix

 

[AJ'S 88NA]

sbenson619, I tried that, but probably didn't put in enough oil for it to make a difference. I'll put more in and check again.

AJ'S 88NA, how can that much carbon build up in only 10,000 miles? Now, when my engine was rebuilt, the shop shaved 0.030" off the head, which is a lot. I calculated my compression ratio at about 9.2:1. It couldn't be higher and not ping badly on mid-grade gas. I thought 215psi was a lot, but it didn't seem out of line for a fairly fresh engine.

After I recheck the compression on #2 with a bit more oil, I'll just put it all back together again, refilling the coolant better to get rid of the air and run it a while until the thermostat is definitely open. If it runs fine, I'll just recheck the compression in 5,000 miles or so and see where it is then.

Asterix

Can't answer that question about the carbon build up, I guess I should have said it's usally the cause of a higher than normal compression pressure. I also can't answer why with 10,000 miles on a fairly fresh motor you have one cylinder down that much from the others.

 

[Asterix]

Followup:

I put it back together Saturday even though I didn't rerun the compression test with more oil in #2. When I refilled the coolant, I jacked the front up a ways and opened the heater valve with my vacuum pump to get the air out. It warmed up fine and the heat did come on. I drove it to the store Sunday and to work today (17 miles of mixed highway/city) and it ran just like it always has.

I'll recheck the compression in 5000 miles or so.

Maybe the shop didn't do quite the valve lap job on #2 they did on the other 5... That's all I can figure since I don't have numbers from right after the rebuild.

AJ, check your compression after 10,000 miles and see how high it is. Some break-in will help for sure. I would expect the pressure to go up some before going back down.

Asterix

 

[AJ'S 88NA]

Followup:

I put it back together Saturday even though I didn't rerun the compression test with more oil in #2. When I refilled the coolant, I jacked the front up a ways and opened the heater valve with my vacuum pump to get the air out. It warmed up fine and the heat did come on. I drove it to the store Sunday and to work today (17 miles of mixed highway/city) and it ran just like it always has.

I'll recheck the compression in 5000 miles or so.

Maybe the shop didn't do quite the valve lap job on #2 they did on the other 5... That's all I can figure since I don't have numbers from right after the rebuild.

AJ, check your compression after 10,000 miles and see how high it is. Some break-in will help for sure. I would expect the pressure to go up some before going back down.

Asterix

I usally check it every 5000 just for peace of mind, if I ever get another 5000 on it as it's been sitting in the garage waiting for me to finish tuning:biglaugh:

 

[Asterix]

2nd followup:

Over my last tank of gas I got 21.7mpg, mixed highway/city. I'd say my engine is fine...

Asterix