Can’t Find Source of Apparent Coolant Contamination

[marysdad]

In June, the oil analysis for our 1999 Ford Ranger, 4.0 V-6, 69000 miles, oil mileage 7002, came back showing high amounts of copper (16), lead (8), potassium (22), and calcium (3443). Blackstone suggested possible coolant contamination, but the values were too low to be certain.

In July, we suddenly experienced missing and rough running, which was traced (by Ford) to the spark plugs. A new set of plugs and it’s run fine since.

At the next OCI (5308 miles in November), we repeated the oil analysis. This time, the abnormal values were copper (17), lead (9), potassium (209), sodium (95), and calcium (3042). Blackstone indicated with some urgency that we indeed had a problem. In addition to the abnormal values, they indicated moisture damage in the additives, a high viscosity reading (96.4), and antifreeze (.19 percent).

Ford ran coolant system pressure, compression, and cylinder leak down tests. The truck passed all three tests with flying colors. Ford says the motor is in great shape. We spoke with Blackstone and they were sure of their results.

We’re stumped and would appreciate any ideas y’all may have as to how we can get to the bottom of this. I’ve posted the full analysis values in the UOA section.

Thanks!

Ralph

 

[medic]

While I'm not sure about the 99 4.0L engines, the early & mid 90 4.0L engines were known for head gasket problems. Typically they would lose a little bit of coolant over a period of time. These were usually very small leaks

Have you been experiencing any coolant loss?

The coolant system pressure check (usually pressurizing the system to ~15 psi & waiting 5 minutes to see if it drops) may not show such a small leak. The other two tests were not going to show anything because the leak is obviously into the oil and not the cyliders.

The UOA results that you posted show that there is a very good chance that coolant is getting into the crankcase due to elevated sodium & potassium. There is some slight elevation of wear metals and I would imagine (you didn't post the numbers) that the viscosity is also elevated. While I am not a professional at interpreting UOA's, this is my opinion and I think other here will agree with me. If you want something you can take to a mechanic who tells you there is nothing wrong, have Terry Dyson (link: http://www.bobistheoilguy.com/terry.html ) interpret the UOA.

I almost forgot -

 

[Chris142]

You can rent a cooling system pressure tester from A-Zone. With the engine off and cold pump the system up.

Look where the intake manifold and the head meet for an external leak. If it runs rough when first started then smooths out after 5-8 seconcs that means coolant is getting into 1 or more cylinders.

 

[jthorner]

It sounds like your engine probably has a head gasket leak. Sometimes those leaks are temperature sensitive and only show up with the engine cold or hot. Traditional pressure tests also are not always sensitive enough to detect leaks in the early stages as it takes a very long time for enough coolant to leak to show up as a drop in system pressure. The leak has to be very big for a pressure test to catch it.

I don't know if the intake manifold on those vehicles alows for the possibility of coolant to oil contamination like many GM engines do, but that is also a possibility.

The bottom line is that oil analysis is a more sensitive indicator of coolant contamination than are the traditional coolant system and cylinder compression/leakdown tests. Unfortunately there are very few techs, service managers or service writers who know jack **** about oil analysis and what it means. These folks generally did not study chemistry or physics with much gusto.

The only surefire way to find out is to pull the intake manifold and heads off and see if there are pathways between the coolant and oil systems. At that point of course you have to replace all of the effected gaskets even if nothing was wrong.

In short, none of the answers are great news

.

John

 

[Gary Allan]

How long were the plugs in before they fouled? This is an unusual occurance on a modern engine without apparent cause. Most give 100% apparent service until changed out routinely. Were the newer plugs, that they pulled to do the compression check, "cherry"? Was it just a select few of the old plugs that were fouled? One bank or the other?

I'm only pointing to the wild card anomaly that also appeared at the same time.

 

[Al]

I completely agree with jthorner above. The leak is small and temperature dependent. Get a Zone Rep from ford to evaluate. Make sure they see the oil analysis. As suggested get Terry Dyson ( www.bobistheoilguy.com/terry.html ) to write a report to get Ford off their duffs.

 

[C4Dave]

The 4.0 OHV engine has known issues with the lower intake manifold leaking coolant into the combustion chamber. You can see it in the middle spark plugs, especially on the driver side. Do a search at Explorer Forum. Lots of information there about the intake manifold leak.

 

[marysdad]

Thanks everybody for all of the good information.

Based on y'all's collective wisdom, it is pretty clear that we have a problem. What is the best way to determine whether the problem involves the intake manifold gasket, head gasket, or cracked head?

 

[Jay]

A leak-down test could also help pinpoint the coolant leak. Use a mechanic's stethoscope to listen for compression leaks.

 

[wileyE]

Sometimes you can put a pressure gauge on the radiator and run the enigine. If the needle twitches up start pulling plugs wires off 1 at a time until it stops. On a V motor this can often at least tell you which cyl, or cyl bank you need a new head gasket on. Can save you from doing both sides.

Does the coolant res level drop? I've got a 5.0 that has drank a tiny bit for 90,000. The motor is so tight and runs so sweet I won't tear into it even though i know it's not right.

 

[t-squared]

When they did the leakdown test they should have seen some discoloration or differences in the plugs of the affected cylinders if the coolant was getting into the combustion chambers. I'm thinking it's leaking into an oil passage via a gasket or a crack in the head or block. You can warm up the motor then put a coolant system pressure tester on it. Leave it on there until the engine cools down completely- as in overnight. This will put pressure on it both hot and cold. You should see a loss in the coolant level and if you drain the oil into a clear container see the 2 fluids separated in there. Not sure if this engine has one or not but the oil coolers that use coolant thru them can leak also. I'm betting a gasket has "gone south" on you though...