The situation when, after a thorough washing of the underhood space or driving through a deep puddle, the car ceases to react to the turn of the key, is familiar to many motorists. Water trapped on electrical connections, sensors and the ignition system causes short circuits or blocks spark formation. Moisture is an excellent conductor of current, which disrupts the normal operation of the electrical circuit designed for a dry environment.
In most cases, panic is early, because modern have a fairly high level of tightness of the main nodes. However, when using high pressure sinks (kerkerkers), a pressure stream of water is able to penetrate protective rubber caps and penetrate into candle wells. It is there that a circuit occurs, because of which the starter turns, but the engine does not catch. The critical point is an attempt to repeatedly start the engine with flooded candles, which can finally disable the ignition coils.
The first thing to do when you find a problem is to stop trying to launch and open the hood for visual inspection. It is necessary to assess the scale of water intake: whether there are visible puddles in the depressions, wet connectors or completely flooded air-intake. Further action depends on how much water penetrated the power supply and engine control system.
Diagnostics of the problem: why water interferes with the launch
To effectively eliminate a fault, it is necessary to understand the physics of the process. The ignition system operates at high voltages, and a certain voltage is required to break the spark in dry air. In the presence of moisture, the resistance between the candle electrodes and the mass (body of the engine) drops sharply. The current goes along the path of least resistance - through the layer of water on the insulator of the candle, and not through the gap of the candle, where the fuel mixture should ignite.
In addition to the ignition system, water can get into connectors. sensor, such as crankshaft position sensor (CRPS) or mass air flow sensor (MMRV). If the water reached the contacts of the ECU (electronic control unit), the engine may not respond to the starter at all or go into emergency mode. Moisture could also get into the air filter housing, which makes it difficult to get air in, although this is less common with standard washing.
It is important to distinguish the symptoms: if the starter spins cheerfully, but the car does not start, the problem is most likely in the spark (candles, coils). If the starter barely twists or clicks are heard, it is possible that water hit the battery terminals or starter, causing oxidation or short circuit. In rare cases, when washing a hot engine, cold water could cause thermal deformation of the metal or crack, but this is already mechanical damage.
Primary actions: drying and inspection
The most important rule is not to try to start the car every 30 seconds. Every failed attempt charges the candles with gasoline and makes the situation worse. First thing you need to do is turn off the negative terminal. batteryto eliminate accidental short circuits when working with wiring. After that, you can proceed to a thorough drying of the under-hood space.
The ideal tool for drying is a compressor or canister with compressed air. The air stream allows you to blow water from hard-to-reach places: candle wells, nozzle connectors and coils. If there is no compressor, you can use a household hair dryer, but with caution: do not heat plastic parts too close and for a long time so as not to melt them. Air temperature It should be comfortable for the hand, not hot.
☑️ Checklist for primary drying
Pay special attention to candles. If you own a car with an engine where the ignition coils are deeply planted (for example, many motors). VAG Group or BMW), water is often stored there. When you remove the coil, you can see the water at the bottom of the well. It must be removed by getting wet with rags or blowing out with compressed air. Also check the coil itself: if there is water inside, it should also be thoroughly dried.
⚠️ Attention: Never pour WD-40 or other moisture disintegrating sprays directly into a candle well in large quantities if there is a rubber seal. Some aggressive chemicals can corrode rubber, leading to air suction in the future. Use special contact cleaners or pure alcohol.
Reconstruction of the ignition system
After the initial drying, it is necessary to check the condition of the candles. If they are wet (from gasoline and water), it is better to twist them and dry them separately, and sprinkle a little into the cylinders. carburettor or alcohol to displace the moisture residue, and blow the cylinders with a starter (with twisted candles and a coil / nozzles disconnected). This will help remove water that may have leaked into the combustion chamber.
If the candles are old, they should be replaced with new ones for the experiment. Wet candles may not give a spark even after drying due to the soda, which in combination with water creates a conductive bridge. Check the high-voltage wires (if you have them on your car) for breakdown. In the dark, you can turn on the ignition and see if the spark “shoots” on the surface of the wire. Water on the surface of the wire is a common cause of current leakage.
The ignition coils also require attention. Examine the rubber cap (tips) of the coil. There should be no water, oxides or cracks inside. If the rubber coil seal is damaged, it does not protect the candle from water ingress during washing. In this case, only the replacement of the seal or the coil itself will help. Gather everything back, making sure all the latches fall into place with a characteristic click.
Can I use WD-40 spray to dry?
WD-40 does displace water, but it’s a temporary solution. The spray contains oils that can collect dust and dirt, creating a conductive plaque in the future. For contacts, it is better to use specialized cleaners (Contact Cleaner), which completely evaporate and do not leave films. WD-40 is an emergency service, but not a permanent means of protecting the electrician.
Checking sensors and electrical connectors
Even if the ignition system is fine, the engine may not start because of "stupid" EBOU, which got incorrect data from wet sensors. Most often, the knee position sensor suffers. If water hits his chip, the signal about the position of the pistons does not enter the control unit, and the spark is not generated. Remove the connector, blow it, wipe the contacts with alcohol and dry.
Also check the nozzle connectors. The water between the contacts can cause a short circuit, which will cause the control unit to cut off the fuel supply for safety reasons. Examine the wire harnesses: are there any cracks on them, through which water could get inside the insulation to the copper veins. If the wiring is old and cracked, the pressure sink could drive water directly to the contacts.
Do not forget about the mass air flow sensor (MMRV) if it is low or not protected by the filter housing. The water hitting the sensor sensor element will distort the readings on the amount of incoming air, and the mixture will either be too rich or too poor to ignite. Gently wipe the sensor body with dry rags without touching the thread itself or the plate inside.
| Engine assembly | Symptom of water intrusion | Elimination method |
|---|---|---|
| Candle wells | Starter spins, no flares, trim | Twisting candles, blowing water, drying |
| Ignition coils | Breaking spark on the body, cracking | Remove the coil, dry the channel and the coil itself |
| Crankshaft sensor (DPCV) | Starter spins, but engine is silent | Remove chips, blow out, dry contacts |
| Air filter | The engine is "pressurized", stalls at start-up | Replace the filter, dry the pipe |
| AKB's Clembs | Weak current, clicks, no reaction. | Remove the terminals, clean, tighten again |
Starting the engine after washing
After all the drying and inspection procedures, you can try to start the engine. Put the battery on. If possible, use a starter or light from another machine to ensure the starter has the maximum current for a confident rotation. At the first start, the engine can work unstable, "trip" or deaf - this is normal, since the residues of moisture and water vapor enter the cylinders.
Let the engine warm up at idle speeds. At this point, you can gently blow the under-hood space with warm (not hot!) air from the hair dryer, directing it to the generator, trampler (if any) and visible connectors. The heat will help to evaporate the remaining moisture. If the engine started and works smoothly, do not shut it down immediately, let it work for 10-15 minutes.
If the engine is started, but is not running stable, try to slightly add gas, keeping the speed at 1500-2000 per minute. This will create more air flow in the cylinders and help burn out moisture residues faster through the exhaust system.
Watch the indicators on the dashboard. If it's on fire. Check EngineThis may mean that the ECU has recorded ignition gaps. In modern cars, the error can disappear after several successful engine start and run cycles. If the error burns constantly, you will need a scanner to reset the error or check the condition of the coils.
⚠️ Attention: If after drying and all attempts the engine does not start, and the starter spins suspiciously slowly or with jerks, it is possible that water got into the starter itself or the retracting relay. In this case, further launch attempts could finally kill the starter. Removal and drying/repair of the starter is required.
How to wash the engine safely
To the situation “washed the engine – the car does not start” is not repeated, it is important to follow the technology of washing. Never wash a hot engine. Sharp cooling of the metal can lead to microcracks in the cylinder head or exhaust manifold. Allow the engine to cool to at least 40-50 degrees (warm, but not hot to the touch).
Use the minimum water pressure. Try not to direct the kerkerker jet directly to the electric connectors, generator, fuse block and ignition coils. It is better to apply a chemical for washing the engine, let it work and wash it off with a weak water pressure or from a hose without a high pressure nozzle. After washing, it is desirable to treat rubber parts and wires with silicone lubricant (not conductive!), which will create a water-repellent film.
To protect candle wells, experienced car mechanics recommend putting special plastic bags on them before washing or using food film, fixing them with a rubber band. This will protect the most vulnerable areas from water jets. It is also possible to remove the decorative plastic engine casing before washing to have direct access for quick drying.
The main rule of engine washing is moderation. Chemistry and brushing are better than high water pressure. Pressure is only needed for the final rinse, and then very neat.
When you need professional help
There are times when self-drying does not help. If after a long drying, replacement of candles and check of contacts the car still does not start, it is possible that the water got inside the ECU itself (control unit) or corrosion inside the connectors, which is not visible to the eye. The gas pump could also fail if water got into the fuel tank through a sapoon (rarely, but it happens when fords pass).
If you hear extraneous sounds while the starter is running or smell the burning, stop trying to launch immediately. The water could cause a short circuit in the wiring, which led to overheating and melting of the insulation. In such cases, a diagnosis of circuit vertebrae electricians and possibly repairing the wiring or replacing the burned fuses and relays are required.
Remember that modern cars are packed with electronics, and the “hydro-impact” is just as scary for electricians as it is for mechanics. If you are not confident in your abilities or are afraid to make things worse, it is better to call a tow truck and deliver the car to a service where there are diagnostic equipment and conditions for high-quality drying in a warm box.
What to do if water gets into the oil?
If you notice that the level of oil has increased sharply, and an emulsion (light foam) is visible on the probe, this is a sign of water entering the lubrication system. In the case of engine washing, this is unlikely if the gasket of the HBC is not pierced due to temperature shock. If this happens, start the engine is prohibited. The water does not lubricate, and the engine will jam after a few seconds of operation. Requires oil change and search for the cause of antifreeze or water in the crankcase.
Can the engine be dryed with a blowtorch?
The use of an open fire (solder lamp, gas burner) for drying the engine after washing is extremely dangerous. You can melt wiring, plastic pipes, fuel hoses or cause gasoline vapor to ignite. It is permissible to use only a temperature controlled construction dryer or a heat gun at a safe distance, constantly monitoring the heating of parts with your hand.
Why is the Check Engine burning after the wash?
Lighting of the Check Engine lamp after washing is most often associated with a temporary violation of the sensor contacts or water entering candles. ECU records uneven operation of the engine (ignition skips). Often it is enough to let the engine work for idle 10-20 minutes, so that the moisture evaporates, and the error disappears itself. If the lamp does not go out after 3-5 cycles of start-warm-up, computer diagnostics is required.
How to protect the water from washing?
A special dielectric lubricant can be used to protect the connectors. It is applied to rubber seals of connectors before assembly. There are also aerosol protective compounds for electrical wiring, creating a water-repellent film. Before washing, critical nodes (generator, fuse block) can be temporarily closed with plastic bags.
How long does it take to dry the engine?
The drying time depends on the amount of water that gets in and the ambient temperature. When using a compressor and a dryer, 30-60 minutes of active work is enough. When drying naturally outdoors on a warm sunny day, it can take 2 to 5 hours. The main thing is to make sure that candle wells and connectors are dry, and not just wait a certain time.