When it’s Time for a Rebuilt Engine Installation – UnderhoodService
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When it’s Time for a Rebuilt Engine Installation

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I noticed the Toyota 4WD truck as soon as I turned into the parking lot on Monday morning. I knew the owner because we’d been servicing his vehicles for a number of years, and I was always impressed by how clean and straight the truck was for its age. It was parked kind of crooked, indicating it was probably towed in, and then I noticed the large oil slick under the engine.

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As I started the computer for the day, I decided I’d better check how long ago we’d seen the vehicle. The last time it had been in was about four months and a little over 3,000 miles ago. We had noted that there may be some timing chain noise; at 200,000 miles, even a Toyota might need some internal repairs. We had changed the oil and the customer had indicated he may sell the truck soon.

The owner called a little later and recalled how the truck had come to be in our shop. After doing his own oil change with this new “trick” thin oil that the kid at the local parts store had sold him, the engine seemed to make more noise than before. And, it seemed to be even noisier after it warmed up. To top it off, on the previous Saturday he had picked up half a ton of pellets for his stove, and the truck seemed to get even louder. On the way back for the second half of the load, the engine just let go. He asked if we could just look at the truck and let him know if it was worth fixing.

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As the day progressed, we found a hole behind the starter that went through to the other side. As we’ve seen several times over the years, a rod had parted company with the crank and, well, you know the rest. I rolled the truck into the shop, put it in the air and surveyed the damage. It would definitely need an engine, but a look at the rest of the vehicle made it obvious that it was worth saving – if the price and availability of a replacement engine was reasonable.

I always like to do a little research before calling the customer with bad news. I knew this customer would not be a problem from past experience, but he would want a lot of questions answered. A call to a local rebuilder verified that engines were available locally, and the price was not excessive, especially considering what the cost of labor would be if we were going to overhaul one of these engines ourselves. I didn’t even have to look for a resale value on the truck as my son had recently shopped for and bought a similar truck. My son paid what I thought was a high price until I looked at a few of them and realized that the market was still very good, even for trucks older than this one. I was even prepared to offer my customer a fair price for the truck if he decided not to have it fixed, knowing I could resell it and still make money.

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I called him late in the afternoon with a guesstimate to see how serious he was about fixing the truck, only to find that after looking into what a new truck was going to cost, he had already decided to fix what he had. He still wanted my opinion, and I was honest in saying that the truck was well worth fixing. I told him I would work up an estimate and call him back.

The Estimate
One thing I’ve learned in doing major work on cars over the years is that the customer will always expect that when you repair his/her car, the repair should last just as long as the part that failed. This is especially true if you’re replacing a major component like an engine. What most customers don’t take into account is that except for the one part you’re replacing, everything attached to it still has a lot of wear.

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On an engine replacement, after finding out what the rebuilder is supplying and what the requirements of warranty coverage are, you’ll need to add certain parts to the cost of the engine to protect the customer’s investment. Even if the estimate seems to come out a little high, build value into the repair by letting the customer know that you’ll stand by your work. The obvious parts you should always replace are the water pump, if not supplied with the engine, and tune parts. Your estimate should also include oil and coolant, just in case there are any warranty problems down the road.

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A check of repair records for the vehicle will also indicate the age of other items such as belts and hose and any past history concerning driveability problems that need to be addressed. Maybe a cleaning service for the fuel injectors is needed. On fuel-injected engines, intake boots and throttle bodies need to be checked and added to the estimate, if needed. If the car has a manual transmission, you’ll want to add the cost of clutch parts, and if the “new” engine doesn’t come with a flywheel, either the cost to resurface the old one or replace it. Some rebuilders require having the radiator cleaned or replaced to secure the warranty coverage, as well as a new thermostat.

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When you call the customer with the estimate, you should also leave some “wiggle” room for items you may find after removing the broken parts. Engine mounts, electrical accessories and emissions components that appear to be in good condition may need replacement after inspection. The guidelines provided by our rebuilder, who is affiliated with the Engine Rebuilders Association (AERA), go into great detail on items to be inspected.

In this case, the estimate for the replacement engine was acceptable to the customer and a go-ahead to replace the engine was given. A call to the engine supplier was made and many questions were asked, some that required a manufacturer date and emissions information. A lot of phone time can be saved if you have all the numbers and information before you make this call.

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Some questions for you to ask are, How “complete” does the engine come?; Does it have a water pump, oil pump, oil pickup, oil pan and all necessary gaskets?; and Are there provisions for add-on A/C? A few other items that may be needed, such as a harmonic balancer and flywheel, may be less expensive if purchased with the engine from the rebuilder. Also ask about the warranty and what is required to maintain it so you don’t miss anything during the replacement that could affect future warranty coverage.

Engine Removal
To save shop time, I recommend not pulling the old engine until the replacement has arrived and has been verified as correct for the application. Unless you have extra shop space to have a vehicle disassembled and unable to be moved, it’s best to make this job a continuous process.

Drain all of the fluids and disconnect and remove the battery if it’s going to get in your way. On Toyota trucks, we always remove the hood (see Photo 1) after marking its location at the hinges. This gives us the needed room to easily get the engine out. Disconnect the exhaust at the manifold and drop it down and out as far as possible, or remove the headpipe if it is in the way. Unbolt the engine from the bellhousing and remove the motor mount to frame fasteners. On some vehicles you may need to remove the starter to separate the engine and transmission. We usually pull just the engine by supporting the transmission with a floor jack. On 4WD vehicles especially, this saves a lot of unnecessary disassembly.

On F1 models, we disconnect and pull the wiring harness out with the engine rather than separating the manifold in order to leave the harness in the car. On some vehicles, this means going inside the car and disconnecting the computer wiring to allow the harness to be pulled through the firewall. Remove the air filter or intake ducting as needed. Pull the radiator, belts, fan and any hose or cables connected to the engine. Unbolt the A/C compressor, if equipped, and tie it up and out of the way to avoid having to evacuate and recharge it. If there’s room, you can do the same with the power steering pump.

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We’ve found that transferring external components is much easier with the engine out of the vehicle. How much you need to remove is pretty much determined by the available space in the engine compartment. Space is a problem on some vehicles, so you may need to remove more items to prevent damage. With the engine hoist in position, pull the engine up slightly at first to make sure that everything is disconnected – some surprise items may include ground cables, hidden hose or wiring clips.

Transferring Parts
This is the important step. Before you go any further, set the old and new engines next to each other and compare them (see Photo 2). Make sure you have the right replacement and that all of the necessary holes, flanges and passages are on the replacement engine. If anything doesn’t appear correct, call the engine supplier. In some instances, an adaptation kit may be needed for certain models depending on equipment. A knowledgeable supplier will be able to resolve those questions before you get too far into the job and start wasting time.

On this engine, it was obvious that since the engine didn’t come with a pan or pickup tube, and the originals were damaged, we needed to order those parts. If the replacement engine comes with a pan, make sure the design has all of the necessary dents and reliefs to fit the model it’s going into.

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After stripping the old engine of manifolds and such, again check to make sure that the manifold flanges and gaskets are going to provide the proper fit and sealing. Also inspect for threaded holes where accessories are mounted, as the replacement engine may not have had the same add-ons and holes or threads where needed. Threads can be added much easier out of the vehicle. You may also need to plug off any oil or coolant passages that are not used for the specific application you’re working on. (The rebuilder may have already supplied the necessary parts for this.)

After this inspection, you should know what additional parts you need, such as engine mounts, gaskets, small hose and various senders. Also check for evidence of corrosion or rust problems (see Photo 3) by closely looking at any steel pipes that carry coolant and replace if necessary. A new oil pressure sender is always a good idea, even if the old one looks good. Having all the necessary parts will make the installation much easier. Don’t forget the new thermostat and filters, as well as necessary tune-up parts, gaskets and seals.

Inspect the manifolds for cracks; excessive carbon may indicate additional cleaning or replacement is necessary. An overlooked vacuum leak source or plugged EGR passage can make starting the new engine a chore, or could lead to premature engine failure or driveability problems. Make sure all external seals are in place and then transfer components from the old engine to the new, inspecting each one in the process. If the engine has a timing belt, make sure the timing marks line up. Install the clutch on the flywheel, if equipped, and make sure any alignment dowels are in place, or “extra” ones are removed.

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Installation
If you have access to cleaning equipment, now is the time to thoroughly clean the engine compartment and make sure that anything connected to the engine, such as battery cables, vacuum hoses, wiring and things like fan shrouds and fuel lines, are in good shape. Replacing them now will save time later.

To make installation easier, I have a collection of alignment studs (bolts with the heads cut off) that will help align the engine to the transmission when working alone, but having another person to assist you is beneficial as well. Being patient at this point also helps, as you need to avoid damage to the new engine and the vehicle while lining up the mounts, the transmission, and the clutch or converter.

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Once the engine is sitting in place, you can reverse the removal procedure to reconnect and reinstall. Use new clamps where needed, secure wiring in its proper place and try to make the reinstallation look “factory.” Run through the vacuum routing to make sure everything is where it should be (it could have been installed incorrectly), and install the new tune parts and set static timing. Depending on which model you’re working on, you may need to set valve clearance before beginning. Pre-lubing is also recommended. Talk to your rebuilder for suggestions.

We use a vacuum-type cooling system filler that indicates any leaks that need to be addressed before filling. Use a good high-detergent oil for the initial fill of the engine. Most rebuilders don’t recommend synthetic oils for break-in, as the engine needs some friction to do so properly. When you’re sure everything is connected, filled and tightened, you can prepare to start the engine.

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Start-Up
Before you start the new engine, be ready with everything you’ll need to make adjustments, including the addition of fluids. Having your timing light and engine analyzer handy will prevent a flurry of running to find what you need. This is a critical time in the life of the engine and may very well determine its long-term durability. Mistakes made in the first few minutes of operation may dramatically shorten the life of the engine.

Run the engine at a high idle until normal operating temperature is reached. Perform tests for proper air/fuel mixture and timing advance, and also check for any codes on vehicles with OBD capability. Check the engine management system to make sure it goes into closed loop, and make sure there’s no exhaust restriction, which can damage the engine in short order.

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An extended road test under normal driving conditions will verify there are no serious driveability concerns before returning the vehicle to the customer. Any problems should be resolved before long-term damage is done. A cool down and restart to normal temperature will verify that the vehicle is ready to go home.

A New Life
This story had a very happy ending. The truck not only looked good, but had like-new power and no unusual noises. The customer was very receptive to the suggestions we gave him about experimenting with unknown “tricks” and proper maintenance. A recheck after the first 600 miles showed that the new engine was going to be a reliable powerplant, as all of the initial adjustments had held. With proper care, a new engine should, in fact, last just as long as the one it replaced.

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Motor Mounts – An Opportunity for an Add-On

Often-overlooked engine components that may need to be replaced when installing a remanufactured engine are motor mounts. These rubber mounts can deteriorate, collapse and/or separate with age.

Fluid-filled “hydraulic” type mounts can often leak, allowing annoying engine vibrations to be transmitted to the chassis. Most mounts are designed so that separation won’t allow the engine to fall out onto the roadway. But a bad mount may cause a myriad of problems – many easily misdiagnosed. Often, bad motor mounts allow the engine to rock and move around, causing noise and interference problems with the throttle, transmission and clutch linkages. For example, a thumping noise when the transmission is put into gear or when the vehicle is accelerating is a classic symptom of a bad mount.

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Excessive engine rocking also can create exhaust leaks and rattles where the head pipe joins the exhaust manifold. Plus, the donut that seals the exhaust joint can be crushed or broken by the motions of the engine, or the head pipe or pipe flange may crack.

Cracked or broken motor mounts can be an annoying source of vibration and noise, typically a clunk or shudder when accelerating hard. A broken or separated mount may even allow an engine-driven fan to scrape the fan shroud or contact the radiator, which also contributes to annoying noise.

Because motor mounts maintain engine and driveline alignment in FWD cars and minivans with transverse-mounted engines, it’s important that the mounts be in good condition. The mounts support the engine and transmission or transaxle, and help dampen noise and vibration to isolate the powertrain from the rest of the vehicle.

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The upper mounts on FWD applications also help control engine rock as the engine applies torque through the driveshafts. While the design of the mount may prevent the engine from literally falling out of the car, it won’t keep the engine from twisting or hopping on its mounts every time the vehicle accelerates or is under load, which can produce thumping and rattling noises. It also can overstress components such as radiator and heater hoses, wiring connectors and the exhaust system.

A broken or loose motor mount in an FWD application can be even more serious because it may allow engine movements that interfere with the throttle or shift linkage.

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If the bad mount is an end mount, it may also contribute to a torque steer condition and cause accelerated wear or separation of the inner CV joints on one or both driveshafts.

The noise produced by a separated or broken motor mount often sounds like a bad U-joint or inner CV joint (a clunk when accelerating or placing the transmission or transaxle in gear). So before either of these other components are replaced, the mounts should be checked. Some mounts are “hydroelastic” and have hollow chambers filled with hydraulic fluid to dampen vibrations that would otherwise be transmitted across the mount to the chassis.

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Motor mounts need to be replaced when they’re loose, broken or collapsed. And, replacement mounts should be the same (fluid-filled hydroelastic or solid rubber) as the original.

Caution: Substituting a less expensive solid mount for a fluid-filled mount can increase the transmission of engine noise and vibration to the rest of the chassis. These mounts may save your customer a few bucks, but won’t do the same job as the original.

They feel harsher and transmit more noise and vibration to the rest of the vehicle, and ironically, may cause a customer to return with complaints of a harsh rides or vibration.

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