Discovery Sport Turbo Replacement, Timing Chain and Thermostat Housing: One 2017 Car, Start to Finish

Quick Answer

Part 1 — the timing chain:

What the Owner Told Us

The complaint was simple. The car rattled on start-up, and it still rattled once it was warm. That second detail matters. A brief rattle on a cold start can sometimes be a tensioner taking a moment to pump up with oil. A rattle that carries on when the engine is up to temperature points much more strongly at a chain that has stretched beyond what the tensioner can take up.

We confirmed the rattle, and when Dan got to the chains the slack was obvious. In his words it was possibly the worst chain slack he had seen, well beyond the manufacturer’s tolerances. The owner had done the right thing by bringing it in when the noise started rather than waiting to see if it went away.

Discovery Sport models have been offered with JLR’s own Ingenium engine family since 2015. If you want the background on why chains on these engines stretch, our guide to Ingenium 2.0 timing chain problems covers the causes in detail. This post is about what one car actually needed.

Stage 1: The Timing Chain Job

A worn chain is never just the chain. The guides, tensioners and gears wear alongside it, and putting a new chain on old guides is asking for the same noise to come back. On this car we replaced all of the chains and the idler gears as a set.

The process Dan follows in the first video is the same one we use on every job like this:

• Strip for access. With the subframe off, the front end comes apart far enough to reach the timing drive properly rather than working blind.
• Fit the new chains, guides and gears. Everything is torqued to the manufacturer’s specification.
• Time it up. The tensioner pins are removed in order — the bottom one first. For the top one, you pull down on the guide until it clicks, then release it.
• Final torque on the camshaft gear. The last stage is torquing the camshaft and variable valve timing gear to the specified angle.

Getting the timing right is the whole job. A chain that is one tooth out can run, but it will not run well, and on an interference engine a bigger error can let valves and pistons meet.

Stage 2: What We Found While It Was Apart

This is the part most owners never hear about, because a lot of garages fit the part they were asked to fit and put the car back together. With this much of the front end already stripped, we inspected everything we could now see. Two more faults turned up.

Part 2 — the thermostat housing and solenoid:

A leaking thermostat housing

The thermostat housing was leaking coolant. On its own, that is a common and fairly ordinary fault. What makes it important on this car is where the coolant was going.

A shorted piston cooling jet solenoid

Dan’s explanation in the video is straightforward. The thermostat housing sits above the piston cooling jet solenoid. When the housing leaks, coolant drips onto the solenoid below and short-circuits it. That is exactly what had happened on this car, so we replaced both the thermostat housing and the solenoid.

The solenoid matters more than its size suggests. Ingenium engines use electronically controlled piston cooling jets, which spray oil at the underside of the pistons to keep them cool. If the solenoid that controls those jets fails, the pistons can run hotter than they should. Replacing only the solenoid would have been pointless — the leak above it would have killed the new one. Fix the cause, then the casualty.

We have a separate explainer on how a thermostat housing leak takes out the piston cooling solenoid, including why it can happen without much warning.

Stage 3: The Discovery Sport Turbo Replacement

The second discovery was the turbo. When Dan checked it, the shaft had excessive end float (in-and-out movement) and up-and-down play, and there was oil on the intake side. A healthy turbo shaft spins on a very thin film of oil with almost no free movement. Once you can feel play in it by hand, the bearings are worn and the turbo is on borrowed time.

Oil on the intake side is part of the same story. As the bearings and seals wear, oil can find its way past them into the intake tract. Left alone, a turbo in that state usually gets louder, loses boost and can eventually fail outright.

Part 3 — the turbo and the finished car:

Getting the turbo out

Because the subframe was already off for the chain work, Dan dropped the exhaust completely out of the way to reach the turbo. As he points out, on a turbo-only job you don’t necessarily need to drop the exhaust from the subframe — it just makes life easier when you are already that far in. That is one of the practical gains of doing everything in one visit: the access work is paid for once.

A replaced turbo also needs the reason for the wear understood, otherwise the new one goes the same way. Our guide to Ingenium 2.0 turbo failure explains the usual root causes we look for.

Why We Did It All in One Visit

Here is the view we hold, and the reason we film jobs like this: the cheapest time to fix a fault is when the car is already apart for something else. Most guides treat timing chains, turbos and thermostat housings as separate repairs with separate symptoms. On a real car they overlap, and the labour to reach them overlaps too.

We have seen the same pattern before on a Jaguar E-Pace, which we wrote up in when a timing chain fault also means turbo trouble. The Discovery Sport went a step further, with the thermostat housing and solenoid on top.

Signs Your Discovery Sport Needs Looking At

Every car is different, and none of these on its own proves a particular fault. But if you own a Discovery Sport, these are the things worth booking in for rather than living with:

• A rattle on start-up that does not clear when warm. That is what brought this car in.
• Coolant going down with no obvious puddle. A slow leak onto a hot engine can evaporate before it reaches the floor.
• A whistle, whine or loss of pull under acceleration. Classic turbo warning signs.
• Oil in the intake pipework or around the turbo. Worth checking at any service.
• Any oil or engine warning messages, even ones that come and go.

It is also worth running your registration through the free GOV.UK vehicle recall checker before any big repair, so you know whether any outstanding recall work applies to your car.

How the Car Went Back

With the new chains timed up, the thermostat housing and piston cooling jet solenoid replaced and the new turbo fitted, everything went back together and the car was returned to the customer. The rattle the owner came in with was gone, and so were the two faults they did not know they had.

Frequently Asked Questions

Hearing a Rattle From Your Land Rover?

Whether it is a chain noise, a turbo whistle or coolant you cannot account for, the first step is a proper look. We will tell you what we find and what it means before any work goes ahead.