I’m travelling to WA this week to pick up a car from my daughter and SIL that they no longer need, and which my college-age son can use as temporary transportation. Actually, it was originally my car, I gave it to them, and now they’re giving it back.
The car is a '96 Ford Taurus with about 130,000 miles on it. Anyway, I talked to my daughter on Saturday, and they had taken the car into the mechanic to have it checked out. He told them that 5 of the cylinders have compression of 130 lbs, but the 6th only has 80 lbs.
I know enough about cars to understand that this is probably not a good thing, but how bad is it? Can I expect that the car will make it from Washington to Utah without collapsing in a heap? What kind of symptoms/problems should I be watching for?
UUHHG - Compression issues…I would think this needs to be taken care of before the trip south. I once had a bonneville with this issue and I ended up blowing a head gasket and a couple of freeze plugs driving only from vermont to Connecticut.
It’s not necessarily that awful. If the low compression is caused by a leaking valve or worn piston ring(s), it may be possible to drive it for quite a while before it really has to be fixed. The power would be reduced (like having 5 or 5 1/2 cylinders instead of 6), there may be some roughness in the engine’s running, and there may be some gasoline dilution of the oil calling for more frequent oil changes.
I would think that if there were a head gasket breach into the cooling system causing that much compression loss that there would already be other significant symptoms like loss of coolant and/or overheating.
For more peace of mind, a cylinder leak-down test should be able to identify the cause of the compression loss. It would also be nice to know if the compression test was done with the engine hot (which is the proper condition for accurate results) and if both dry and wet (adding oil to the cylinders to check for worn rings) tests were done.
I would expect ring wear to be more or less even. A problem with just one cylinder would have me looking at the valves first. I once ignored a “tick” associated with a substantial loss of power (4 banger) & rough idle. Ignored it right up until a bit of valve broke off into the cylinder. It’s about 12 hours between Seattle & Salt Lake with not a whole lot in between. What could possibly go wrong in just 12 hours?
Thanks, all. I’ll let you know Monday if I get back OK. The problem is that I don’t want to spend more fixing the car than it’s worth, so we’ll cross our fingers and see how long she lasts.
A compression tester is pretty cheap…around US$20.
Pour a teaspoon of oil into the cylinder with low compression. If this greatly improves the compression, then you probably have a broken ring . In this case, it is probably OK to drive. If the compression stays low, you have most likely valve problems. A leaky valve is going to get much worse in short order: The leakage of hot combustion gas will quickly erode the valve and seat.
You might make the same diagnosis without the compression tester. A broken ring will produce lots of crankcase blowby. Open the oil filler, and it there is a lot of hot gas coming out, a broken ring is a good bet. Do this with a presumed good engine of similar displacement to get a feel for what is normal and what is excessive.
I second GaryT (not that he needs to be seconded) in that more info would be helpful. In addition to the details he mentioned, it might be helpful to know if the engine is the 3.8, whether combustion by-products are detectable in the coolant, and whether any other symptoms or drivability problems are showing up.
Personally, without knowing all the facts, I would generally be reluctant to put any serious money into this vehicle (especially if the engine is the 3.8l V6), due to potential head gasket and transmission problems that may lie ahead.
Actually, the car I’m talking about has the standard 3.0L engine, not the 3.86. However, I’m still hoping I don’t have to put a lot of time and money into it to make it driveable.
I’m a little more than curious why the mechanic that originally did the compression test didn’t do both a dry and wet test – first without adding anything to the cylinders and then adding a small amount of oil in the cylinders that are low on compression for comparison purposes.
Having said all that, it seems to me that if the engine is running smoothly, at this time it is probably not too terribly serious and will probably be OK for the trip. But keep in mind, it won’t fix itself, so eventually it will have to be repaired. (Or traded off. )
Update for those who are interested. I picked up the car on Saturday in Bellingham and drove it back to Salt Lake with no mishaps. I’m still planning to get the engine checked out and see what it will take to fix the problem (if it’s worth it). Thanks again for your advice.
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