Unfortunately sometimes engines fail and if you have an older vehicle that is in relatively good condition and it is a desirable vehicle you will want to replace the engine the correct way so that it lasts for many years to come.
In this How To we will go over some of the parts that you should should change when installing your replacement engine. Although you paid a good amount of money for your engine you want to make sure that it has the best chance to survive and run well. Some of these parts and repairs are optional and it will depend on how you serviced your old engine and vehicle.
Harvesting spare parts from your engine if you need to return a core engine or even if you are just discarding your engine is a good idea. Its not that you want to swap them over to the new engine right away and new parts is what we are suggesting but if you just replaced all of your coils and plugs 3 months ago then swap them to the new engine without any question.
Parts That Must Be Replaced When Doing An Engine Swap
The first parts that must be replaced when swapping an engine are the thermostat and the water pump. These two parts are relatively inexpensive and they mean a lot to the health of your engine. If your engine has a Timing Belt that drives your water pump then you should get an entire kit that includes the water pump, timing belt, tensioner pulley, and other assorted seals and parts. They are normally inexpensive and you have no idea when the belt on your used engine was last replaced so a timing belt replacement is a necessity and doing it when the engine is out of the vehicle is much easier. If your engine has a timing chain then check the replacement interval for the chain inspect it and its guides and consider replacing it. However the water pump and thermostat are not an option they must be replaced with new parts.
The VVT Valve is the next part you should either replace or service and clean is your Variable Timing Control Valve or VVT these valves tend to get filled with gunk because oil flows through them to adjust the timing on your valves. You should replace it with a new one but at the very least you need to service and clean it. If you are servicing your VVT valve you will need to buy new O Rings.
Vacuum Lines should all be replaced with new line. You can purchase bulk vacuum line from your auto parts store but make sure that you are not buying windshield washer pump line. You need to get line that is able to deal with the vacuum pressure and also petroleum gases. You can cut a small piece of hose and then check the internal diameter of the hose with a drill bit to find the correct size.
PVC Valves should also be replaced as they don’t cost that much and can fill up with gummy oil residue that makes them not work as well. You can also just service many PVC Valves by using Carburetor Cleaner or soaking the valve in a parts washer. Often it can be difficult to get to the valve with the engine in the vehicle so replace it while the engine is out of the vehicle.
All Engine and Transmission Fluids must be replaced and this should not even be a question. You should never even start your engine unless you have drained and installed new oil and a filter. For transmissions you should never reuse old fluid and you should clean any screen and change any filter.
Parts That Have A High Priority To Be Replaced During An Engine Change
Coils, Plugs, Wires are not a necessity like your timing belt and water pump but it is a really good idea to change these wear items with new parts. If you are swapping the exact same engine then you can swap over good parts if they are relatively new. For the cost of the items it is really a good idea to change them.
O2 Sensors are also something that should be replaced as they can effect the emissions and performance of the vehicle. Replace them when the engine is out of the vehicle.
Engine and Transmission Mounts are not a necessity to replace on vehicles with low miles but if you have over 150k miles and you are swapping your engine then you can bet that your engine mounts have a good amount of wear. They may still work but the rubber has likely been compressed a lot over the years. If they are cheap then replace them while the engine is out.
Final Note
The parts above are really not optional when replacing your engine but in some instances if you are on a tight budget then the cost of throwing another couple hundred dollars in parts at your new used engine might be prohibitive.
On the other hand the water pump and thermostat must always be replaced and like we said on engines with a timing belt driven water pump you need to get the full kit for $150 and replace it all. It is just good insurance and you won’t be fighting in cramped places trying to replace it in another 25-50k.
Things that we didn’t list might be fuel injectors if they are inexpensive and sensors. Replacing sensors that cost under $10 each is really a no brainer. If you have your engine out and you can change your oil pressure sensor and water temperature sensor then you should do it.
Also depending on how you purchased your new used engine you might need to return your old one for a core charge. Remember to harvest any parts that you can use later especially parts that you may have just installed.
Also its not a bad idea to call your manufacturer’s local service department or stop by and ask them for any suggestions on what parts you should service or replace while the engine is out. Normally they will be helpful or maybe try the parts department.