Car Experts!

I have a 1990 Crown Victoria that has had a problem with leaking/burning oil for about a year (I can tell the burning from the smell - I’m unsure if the engine is also burning it internally or if it just the stuff that leaks out onto the engine that gets burnt). My mechanics have tried fixing it various ways with little success - they say they themselves are unsure where the leak is. What I know is that it is close to the back of the engine compartment, i.e. close to the driver).

About a week or two ago the car failed inspection for exhaust. Also, my wife was checking the oil level and the tube that the dipstick goes into came away in her hand, along with the dipstick itself.

The mechanics now say that the entire engine is disintegrating, which caused the dipstick thingy to come off. And that the exhaust failure was due to “blow-by” (IIRC), another product of the engine disintegration. In their opinion, the thing is ready for the scrapheap.

But I have some lingering doubt. I’ve driven cars with engines that were on their last legs, and one standard feature of such cars has been a significant loss of engine power, usually accompanied by an increase in chug-a-lug engine noise. In this case, neither symptom is present at all - the car drives as strongly and smoothly as ever.

So the question is how possbile is it that the whole mess is the result of the dipstick thingy getting loose and causing a leak (this happens to also be the location that the oil leaks from), and the “blow-by” thing is hot air?

I don’t have an answer to your question (sorry, cars aren’t my strong subject), but it’s good to see you back. I was begining to wonder what happened to you…

Zev Steinhardt

Just curious, but what engine does it have in it, and how many miles?

Take a look at the catalytic converter, and see if there isn’t a 1" manifold that attaches to it. (The other end should eventually connect to the smog pump) Check (while cool, of course) to see if the manifold hasn’t disintegrated at the attach point. There also should be a check valve on top of the manifold, that may be clogged with manifold remnants. It gets way hot at that connection point, and I had the same problem a few years ago with my van, and it took me a while to finally figger it out. The extra noise from the broken manifold wasn’t really that noticeable. I replaced the manifold (about $35 IIRC) and haven’t had another problem with it passing inspection.

The engine burning could be a leaky valve cover gasket, or possibly the rear seal is leaking onto the exhaust, and that’s why you can smell it, but there’s no evidence. I’m in agreement with you, this engine probably is salvageable. At least it should be provided it received decent maintenance.

As for the dipstick coming off in your wife’s hands, well, it beats the hell outta me, but sounds like a great set-up for a “don’t let her give you a hand job” joke.

But then again, wtf do I know.

This makes absolutely no sense to me. What do they mean “disintegrating?” Is the actual block “disintegrating?” I fail to see how that could happen, nor how a “tired” engine could let the dipstick tube come loose. Tubes do come out, but I fail to see how they could really be tied together.

Oil burning is a really, really obscure symptom. It could be valve seals, working past the rings (which they probably mean by “blow-by”), a simple gasket leak, rear main… etc, etc. Or a combo. Is it buring blue from the exhaust? That means its burning internally. Is it worse when the engine is cold? Usually this means an internal sealing problem… could be indicative of valve seals but not by any means exclusively.

Get your mechanic to do a compression test if he hasn’t already. They should help him pinpoint the problem, or at least narrow it down.

How many miles on the engine? I am guessing its a 302 which is a pretty strong engine. With proper maintainence it should last upwards of 160K miles before a rebuild IMHO… but of course thats just a guesstimate I pulled out of my ass.

My guess is that the piston rings have some wear, which wouldn’t be out of line for a Ford 302. Of course this has nothing to do with a loose dipstick mount! But, it jives with the oil burning issues. Yes…blue smoke in the exhaust will be an indicator.

Runs smooth? Well, this is possible. It is possible that it burns a little oil that gets past the piston rings, and the engine compression and plugs are such that it doesn’t impact things all that much interms of power and drivability.

You could live with oil burning, but shouldn’t for emissions concerns. Looks like you flunked tests…so…

I’s inquire about the compression test and possible ring wear. The cost of a ring job on your car might be scary considering it’s real world cost.

Find a different mechanic. Tell the new mechanic to steam clean your engine so it’s easier to find a leak (or leaks). Buy some Stop Leak (sometimes it works). Try a heavier weight oil.

When oil is burnt inside the engine (in the cylinders), it typically comes out the tailpipe. If there’s a significant amount, there’s generally pale blue smoke. Unless there’s an exhaust leak in the area you describe–which I assume would be quite noticeable–there must be external leakage dripping into that area. In hard to find cases, adding leak-detection dye and inspecting with an ultraviolet light should show where the oil is coming from.

I assume this means the content of the exhaust gases failed a tailpipe emissions test. Blow-by could be another symptom of the problem that’s producing excessive emissions, but it wouldn’t actually be the cause of those emissions. Blow-by is the presence of combustion pressure in the crankcase.

If the tube came out whole, I would expect a missing fastener or broken bracket if it’s held in that way, or some looseness in the fit between the tube and the block if it’s just a snug-fit type retention. If the bottom of the tube has eroded away, I would suspect rust or similar corrosion.

“Disintegrating” is not a helpful term in evaluating the situation. Blow-by would be a result of combustion gases getting past the rings, the cure for which is generally an engine overhaul (at least a ring job, but usually if the rings are significantly worn, other internal engine parts are also). Blow-by might have contributed to the formation of corrosive compounds that eroded the dipstick tube. It’s not that blow-by causes excessive emissions, but that worn rings can cause excessive emissions and can also cause blow-by. It’s plausible that the engine is nearing its end.

Not all engine wear situations exhibit the same symptoms at the same time. Your car may indeed reach the state you describe, but the fact that it still runs well doesn’t disprove the possibility that ring wear is causing excessive emissions.

With the dipstick tube gone, I would expect leakage from its hole. I wouldn’t assume that it’s the only oil leak, though, since presumably it’s been leaking for a year. I don’t see how this would have any effect on what comes out the tailpipe. There may or may not be blow-by, but if it failed an emissions test there’s something going on unrelated to external oil leakage.

The simple check for blow-by is to remove the oil filler cap and, with the engine running, feel with your hand for a little air pressure coming out the filler hole. It can almost be like holding your hand an inch from the end of the tailpipe (but it won’t be hot). Sometimes it has a noticeable pulse to it. Compare with several other cars to get a clear idea what’s normal.

This is an area where the PCV system could have an effect. I’d recommend making sure the PCV valve and the system as a whole is working okay before making a final determination.

How many miles has it done?

If an engine’s burning oil it’s usually fucked mate. More trouble than it’s worth. Get a decent car that isnt on it’s last legs.

Thanks to all who have responded (including Zev - hi there!).

As for specifics:

I don’t know what engine it is - it is definitely an 8 cylinder, and I think it is 5.0 liter. I don’t think I will be doing any major engine overhauling in any event, as the car has other troubles with it’s electrical system (power locks & windows, gas gauge, radio etc. etc.) But if it can be cured for a few hundred, I’m game. The car itself has 111K miles on it (mostly city driving).

I wouldn’t know anything about the catalytic converter manifold or the like. I know we recently had some exhaust work done, and the place that did it is pretty thorough, generally.

I checked for blue smoke out of the tailpipe. The car was in idle, but I asked my wife to press the gas a few times. Nothing that I could see.

The dispstick tube came out whole in the sense that the end of it is not eroded at all, as far as I can see. But there is some sort of clamp midway up the tube, and this fastener is rusted through.

I tried taking off the oil filler cap and feeling for air pressure. Nothing that I could feel, at all.

Former Ford mechanic, current parts counterman here. The 5.0 l engine is strong, but it has a few “quirks” One is a hidden filter below the PCV valve which is hardly ever replaced. When this filter clogs, and it will, the PCV no longer pulls the blow-by gases out of the crankcase. It is a bear to get at as the valve is in the back of the engine, close to the fire wall. Have someone remove the PCV valve and probe in the hole with a pair of long nosed plyers. If you find an obstruction, pull it out. A small cylinder made of sheet metal, with a steel wool center. Replace it. Good luck finding one at a parts store. IIRC it is a Motorcraft FA-1062. I could be wrong. After you replace this the PCV should pull a fair amount of vapors. Since the crankcase should be under a vacuum it will slow down leaks.
This engine also has a weak seal to its intake manifold, it will leak out the back, run down the transmision bell housing, making a mess. Have the gasket set replaced. This should solve most of your problems.
Keep us updated. Thanks

Booker’s advice about the PCV filter offers some good insight. I think it makes sense to get the PCV system working properly and then retest the exhaust emissions.

Although he’s likely right about the intake manifold gasket, keep in mind there’s a bit of a risk in doing a repair without definite test results.

You should be able to get a new dipstick tube from a Ford dealer (I’m assuming the clamp you mention is an integral part of the tube). If it uses a seal where it goes into the block, make sure you’re getting that as well.

It’s hard to get a full picture of a situation in this message board medium, but I can’t help but suspect that the shop you’ve been dealing with is lacking. Equating the dipstick tube bracket rusting through with the engine as a whole “disintegrating” does not compute. In any case, I think it’s wise to get a second opinion about all the items you’ve discussed.