Fluid Loss and Intermixing BY mike mavrigian When separate engine fluid circuits meet, bad things happen.

It’s obvious that engine fluids must be isolated within their covers. Add engine oil and a new filter, run the engine for a day, individual flow circuits. Mixing any combination of fuel, oil then perform a complete oil and filter change. and/or coolant is never a good thing. Here, we’ll touch on the While milky or coffee and thick creamy evidence on a various issues that can occur. dipstick is one of the traditional indicators of coolant in oil, this may not always be the case with today’s detergent oils that COOLANT IN OIL may tend to hold coolant in suspension. However, since glycol If the engine is “using” coolant but you can’t find an external exudes a “sweet” odor, sniffing the dipstick can provide a clue. leak or there’s no excessive steam exiting the pipes, check the oil Bear in mind that all engine oils may contain a small level in the sump (dipstick check) for an overfill condition. Also, amount of water due to condensation during cold/hot cycles. if coolant has contaminated the oil supply, the oil will be milky Minute amounts of water tend to boil and steam-out when or brownish and thick, appearing more syrup-like. If oil enters oil temperature hits about 212 degrees F. The PCV system (if the cooling system, the coolant will turn a darker color. applicable) draws this moisture out of the crankcase. However, a Coolant can migrate into the oiling system in a variety of coolant mix features glycol, which does not boil away, but forms ways, including an improperly sealed head gasket allowing acids that thicken the oil and reduces the oil’s ability to flow coolant to seep into an oil passage at the deck. This could be as required. The acids begin to attack metal surfaces, which, caused by debris trapped between the head gasket and deck, depending on the severity, can cause corrosion, which can also allowing a travel path for the coolant. An erosion spot on the result in the creation of metal particles that attack bearings, block or head deck can also provide a minimal or no-contact in addition to the harm caused by reduced lubricity being area of the head gasket. A cracked wall can allow delivered by a thicker concoction of the blended oil and coolant coolant from the water jacket to enter the crankcase. In some milkshake. cases, a cylinder wall can crack in an application where the OIL IN COOLANT cylinder wall thickness is minimal, adjacent to a head stud If the engine’s coolant appears milky/brownish and “thick,” location, where the head stud was locked in place with a engine oil has entered the cooling system. The most likely cause chemical thread locker compound, where the thread locker may be oil galleys in an aluminum head opening up into a water expanded as it cured and placed stress against the cylinder wall. jacket as a result of overheating, which can result in a warped I don’t see this as a common issue, but it can happen. Due head. In this case, the head gasket may not be able to retain its to stupidity or simply as the result of a sleep-deprived mistake seal. In addition to head warpage, other possible causes might during a long night of thrashing to prep a vehicle, let’s say that include erosion in the deck(s), improper head gasket installation coolant (water or an antifreeze mix) was accidentally poured or improper deck surface finish. into the crankcase. Hopefully the mistake is caught before the Note: If you observe small dark spots in the coolant (when engine was started. Allow the engine to sit, un-started, for at viewing coolant after removing the radiator cap or in the least one hour. This will provide time for the coolant to settle overflow tank), while the coolant appears to be otherwise clear in the sump, below the oil (remember that oil and water will and not milky, if you’ve added a “water wetting” agent to the separate, with oil floating on top of the water). Drain the sump coolant mix, this could be quite normal and not a cause of to drain the coolant, until you see several seconds of only oil concern. However, there have been reports of certain brands of draining out. Replace the drain plug and adjust the oil level if a water wetting agent that eventually makes the coolant look needed. Operate the engine for at least several hours (or for a like it’s contaminated with engine oil, with a brown, sludgy day or two). Then perform an oil and filter change. This should appearance. This can fool someone into assuming that engine remove trace amounts of coolant that remained in the oil circuit. oil is entering the cooling system. A water wetting solution is If the coolant contamination is realized after the engine was intended to improve heat transfer and to reduce the presence started, immediately drain the oil and remove the oil filter (the of air bubbles which can result in cavitation. Without further filter must be removed and discarded because it now contains research, I tend to think that in most cases where a customer a degree of coolant). In order to give any water a chance to claims that this additive has created the issue, pinpointing the evaporate, leave everything open to air (leave the oil pan drain real cause of the discolored coolant remains important to rule plug off, leave the filter off and remove the covers). This out any potential for oil entering the coolant. may be a waste of time, but it can’t hurt. Leave these items off Another potential cause of oil entering the coolant supply is for a full day before reinstalling the drain plug, filter and valve a faulty oil cooler, if the oil cooler depends on heat dissipation

58 APR-JUN 2018 engine professional If an aged block is to be bored to an oversize, it highly advised to first check cylinder wall thickness with a sonic thickness gauge. In this example, a check was not performed. After the cylinders were bored and finish-honed, a small dark spot was observed during assembly. Upon closer examination, the “spot” was a hole open to a water jacket. The iron in this location was in fact so thin and weak that the builder was able to push it open with finger pressure, revealing a hole about 0.500” in diameter. Naturally, a sleeve installation was required to save the cylinder. If this was not caught in time, coolant in the number 4 cylinder in this old Mopar block would have immediately started to enter the crankcase, with eventual catastrophic issues. by running through the radiator, since oil pressure is higher than coolant pressure, where a pinhole or crack in the oil channel can allow pressurized oil to force its way into the coolant. Naturally, if the engine oil cooler is remote, featuring it’s own dedicated oil-to-air heat exchanger and independent of the radiator, this would not apply. A potential cause for oil contamination into the cooling system involves cracks or pinholes in a casting’s oil galleys. Dry bench pressure testing (where a soapy solution is sprayed onto the surface during pressurization) may not reveal this issue. Submerged pressure testing provides a much better inspection for internal flaws that would otherwise be missed.

FUEL IN COOLANT This may be more of an issue with diesel engines, where cups/O-rings are bad or not installed correctly. This can allow diesel fuel to enter the cooling system. In severe cases, this can require not only injector service (or even cylinder head) The dreaded “milkshake” observed during an oil change is an absolute replacement), but flushing or replacement of the water pump, indication of severe coolant migration into the crankcase. heater core and all cooling system hoses.

HEAD GASKET “fuse” in a combustion/oil/coolant leakage issue. As with a All too often, we hear the phrase “head gasket failure.” Yes, a fuse in an electrical system, a surge or failure of something in head gasket can fail, but it’s extremely rare that the head gasket the circuit caused the fuse to fail, while the fuse itself was not was at fault. Rather, head gasket failure is a result of being acted at fault. Head gasket failure is a symptom that a mechanical upon by other issues. The head gasket can be considered as a issue is present, whether that involves improper cylinder head

www.engineprofessional.com 59 fluid loss BY mike mavrigian

clamping, a distorted block or head deck surface, improper deck surface finish, a contaminated deck surface, a crack or erosion issue in a cylinder , block deck, head deck or combustion chamber. Other possible sources, depending on engine design, include improperly sealed head bolts, where head bolt holes are open to water; improperly machined intake manifold mating surfaces and/or intake manifold bolts that may be open to water; and (again, depending on engine design), improperly sealed engine oil coolers, water pumps or timing covers. It’s not uncommon for many engine blocks to feature head bolt holes that are open to water. If the female threads are stripped, this poses a dual concern not only of water migrating along the head bolt threads but insufficient head bolt clamping, which is turn can lead to head gasket failure. Considering the materials, design and quality of today’s performance MLS gaskets, it’s extremely rare that the head gasket itself caused the problem. If the head gasket has failed, “the fuse blew.” Look for the cause of the problem instead of blaming the gasket. Oil rises to the top of water and is held in suspension. But when oil enters the cooling system and is circulated under pressure, a thick mixture results. HYDRAULIC LOCK If coolant or an excessive amount of fuel enters the cylinders, this can potentially result in a hydraulic lock. Since fluids are not compressible, if enough fluid is displaced between the and combustion chambers, this can prevent the pistons from travelling to full top dead center, placing destructive resistance force between the pistons and rod bearings and rod journals. This can easily result in bent connecting rods, destroyed bearings and depending on the forces involved, a broken and a severely damaged block. If forces are significant enough this can even attempt to push the cylinder heads from the block, potentially involving failure of head fasteners, head bolt threads pulled out of the block, warped or fractured head, etc. Not a pretty sight. Depending on when hydraulic lock occurs, this can either prevent the engine from firing or, if occurring during a high engine speed event, this can spell catastrophic engine failure. Any evidence of fluids entering the cylinders requires immediate diagnosis and correction, hopefully before damage can occur. Verifying cylinder wall thickness prior to boring can save precious time FUEL IN OIL and avoid thin spots that can lead to water jacket exposure, cylinder wall Excess fuel entering the oil system is obviously a bad thing. In weakness/distortion, ring damage, etc. a gasoline-fed engine, a small amount of fuel entering oil isn’t uncommon, due to conditions such as cold starts, too-rich carb mixture setting, leaking fuel , etc. In general, if the amount of fuel in the oil exceeds about 2%, this is enough to dilute the oil and lower viscosity to the point of potential inadequate lubrication for bearings, valve guides and all frictional areas. Even if the fuel-in-oil issue is minimal, this is yet another reason to be diligent about performing oil changes. Personally, I never wait until vehicle maker “extended interval” mileage levels are reached. Regardless of how long, in theory, the engine is rated to run between oil change intervals, I never exceed 5000 miles on the oil supply. I’d rather spend more on oil and filters than take a chance of compromised oil viscosity that may be caused by the introduction of fuel. Drag engines that run nitromethane fuel can be difficult to start until the engine spins fast enough and builds some heat. A common practice is to use gasoline or alcohol to get the engine to spin before feeding nitromethane. Failure to get the engine spinning fast enough before you have controlled ignition that a hydro-lock can occur, potentially blowing the cylinder heads off Checking deck flatness/uniformity is critical. Uneven, scored or excessive the block. Excessive fuel wash can enter the crankcase, severely surface finish roughness can easily lead to head gasket failure.

60 APR-JUN 2018 engine professional fluid loss BY mike mavrigian LS ENGINE PARTS

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62 APR-JUN 2018 engine professional fluid loss BY mike mavrigian

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Mike Mavrigian has written thousands of technical articles for a variety of automotive publications and many books for CarTech and HP Books. Contact him at Birchwood Automotive Group, Creston, OH. Call (330) 435-6347, email: birchwdag@frontier. com or go to birchwoodautomotive.com.

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64 APR-JUN 2018 engine professional