Preparing the BMW M51 Cylinder Head for Installation – Range Rover P38

Over the past few days, I prepared the new cylinder head for installation. If everything goes according to plan, I should receive the correct head gasket today.

Earlier, I was still on the fence about using an alternative gasket that lacked the rubber seal at the water pump outlet. Because of that missing seal, I wasn’t comfortable installing it and decided to postpone the job until the correct gasket was confirmed.

Today that confirmation finally came, so installation can move forward as planned.

Below are a few pictures of the new cylinder head, with most components already installed and ready to go.

Soon installation time!

Range Rover P38 Cooling System Troubleshooting Update – BMW M51

Over the past weekend, I finally managed to find some time to take a deeper look at the P38. The goal was to pinpoint the exact cause of the issue — whether it was a failing head gasket or something else entirely.

To eliminate the possibility of air being drawn into the cooling system through a leaking radiator or degraded hoses, I decided to proactively replace several key components.

I replaced:

• The radiator

• The bypass hose at the rear of the engine

• The hose between the thermostat housing and the heater core

• The thermostat O-ring

• The water pump

The radiator was already on my replacement list. I opted for a thicker aluminum performance radiator, which offers increased cooling capacity compared to the original unit. This upgrade not only improves heat dissipation but also helps rule out radiator-related issues during troubleshooting.

By replacing these components, I could confidently exclude common failure points in the BMW M51 cooling system and focus further diagnostics on the root cause of the problem.

Link to Direnza radiator:
P38 DSE Direnza Aluminum Radiator

P38 diesel Direnza performance radiator

Cooling System Pressure Test Results – Range Rover P38 BMW M51

To further diagnose the issue, I performed a cooling system pressure test. Starting at 15 psi, the system consistently lost around 2.5 psi within a few minutes. In my view, that’s still problematic and indicates that something isn’t right.

While the system was under pressure, I carefully inspected all hoses and connections for visible coolant leaks. No external leaks were found. I also checked the heater core area, but since the heater matrix had already been replaced and is fitted with relatively new O-rings, the likelihood of a leak there was minimal.

With no external leaks present, this strongly suggests an internal issue.

At this point, the only remaining logical conclusion is that the cylinder head will need to come off for further inspection and replacement.

More on this soon 👊

Range Rover P38 Cooling System Problems – From Road Trip to Head Gasket Failure

It might not come as a surprise, but at the moment the P38 isn’t running particularly well.

That said, I did drive it last summer — well, towards the end of summer — all the way to the Alps. I couldn’t use it earlier in the season because the transfer case and torque converter still needed to be replaced. Once that work was done, I decided to take it on a proper test: a 2,500 km round trip.

Apart from some overheating brakes, the journey was completely uneventful. That trip finally cured me of the infamous “P38 paranoia” and gave me the confidence that I could just hop in and go anywhere.

---

When Things Went Wrong

That confidence lasted right up until a trip to the Belgian Ardennes.

Halfway down the motorway, I suddenly saw steam coming from both the front and the rear of the car. With my heart in my throat, I was luckily able to pull off at a nearby petrol station.

There, I discovered that the top right radiator hose had come off, dumping all the coolant. I took a moment to regroup, grabbed my tools, bought several bottles of water, refilled the system, and carefully drove home at a very conservative pace.

Once home, I parked the car and wanted absolutely nothing to do with it. I was completely gutted.

---

Initial Diagnosis

About a week later, I started looking into the problem more seriously. I ordered a combustion leak tester and fluid to check for a possible head gasket failure. The fluid did turn yellow — although it took quite some time, which already raised some questions.

To better observe what was going on, I installed a transparent hose between the top of the radiator and the expansion tank. This allowed me to visually monitor the coolant flow. I noticed bubbles in the line — sometimes steady, sometimes none at all.

The cooling hoses also became slightly stiffer once the system was closed and pressurized. That in itself isn’t abnormal, as long as they don’t become rock-hard.

I then used an Amazon pressure tester and confirmed that the system was losing pressure. Unfortunately, at that stage, I still couldn’t pinpoint exactly where.

---

Parts Replacement & Escalation

At that point, I started sourcing parts to eliminate potential failure points. I ordered:

• A new water pump

• Thermostat O-ring

• Bypass pipe behind the engine

• An aluminum radiator

• A head gasket

• New head bolts

• Additional gaskets

With the BMW M51 diesel, things get tricky. Once the cylinder head is warped, skimming is not recommended, as it can lead to cracks around the swirl chambers.

I always believed new cylinder heads were essentially unobtainable — until I discovered that AMC had just produced a new batch. I didn’t hesitate and ordered one immediately. Even if it turns out not to be strictly necessary, I’m happy to have one available just in case.

---

Looking Back

If you’ve been following the blog for a while, you may remember that I overhauled the engine about two years ago. At the time, I inspected the cylinder head and already knew it wasn’t fully within specification for longitudinal flatness. If memory serves me right, the limit is 0.10 mm — and mine measured somewhere between 0.10 and 0.15 mm.

According to RAVE, these heads should not be skimmed, so back then I decided to take a calculated risk and reinstall it anyway. That gamble paid off — at least until now.

---

What’s Next

At this point, I have nearly all the required parts on hand. I’ll continue troubleshooting for a bit longer before fully committing to removing and replacing the cylinder head.

More to come.

By the way some pictures for your enjoyment ✋

KTM 1090 Adventure R vs Ducati DesertX – Specs, Design and Philosophy Compared

Spec Comparison

When you compare the KTM 1090 Adventure R with the standard Ducati DesertX, it becomes clear that the two bikes are actually quite close in terms of specifications and overall concept.

In fact, I wouldn’t be surprised if Ducati closely studied the KTM during the development phase of the DesertX. When you look at the geometry, suspension travel, wheel sizes, and intended use, there are clear similarities between the two machines.

Both bikes are designed as true adventure motorcycles with a strong off-road focus, rather than oversized touring bikes that only pretend to handle dirt. The overlap in specs suggests that Ducati aimed directly at the same segment KTM has been dominating for years.

---

Specification Sources

The comparison below is based on official specification sheets from the manufacturer:

• KTM 1090 Adventure R – Specifications

• Ducati DesertX – Specifications

Source: https://www.motorcyclespecs.co.za/

KTM 1090 Adventure R

Ducati DesertX specs

KTM 1090 Adventure R Project – Buying Used, Full Inspection and Baseline Rebuild

I wasn’t sure if I was going to buy another motorcycle. I hadn’t ridden my previous bike all that much, and once the P38 Range Rover entered my life, time became scarce. On top of that, I never really bonded with the Ducati — something just didn’t click.

Then the P38 broke down again, and that got me thinking. Maybe keeping a bike on the side wasn’t such a bad idea after all. I had already postponed trips because of P38-related issues, and I’m starting to believe that’s simply part of its nature.

So I began looking at motorcycles again. After all, riding has always been my first — and fiercest — passion.

---

Back to Bikes

The current adventure bike market has absolutely exploded, but not necessarily in a good way. It seems manufacturers believe we all need screens everywhere and endless accessories, while those “farkles” have somehow become more important than the bike itself and its performance.

I see a clear parallel with the automotive industry: downsized engines everywhere — with a few exceptions. KTM is one of the brands that continues to increase displacement and horsepower, staying true to its own slogan:

“Ready to Race.”

That mindset led me straight to the second-hand market. I initially test-rode a KTM 1190 Adventure. Purely by chance, I also went to look at a KTM 1090 Adventure R — a bike that wasn’t even on my radar.

I bought it after riding it for no more than 200 meters.

Instantly, I remembered why I like KTMs so much. There’s just something about the way they deliver power — it puts a smile on your face immediately.

So, let me introduce my new-to-me 2017 KTM 1090 Adventure R.

---

Reality Check

That’s not to say everything went smoothly.

I bought the bike from a guy who owns a car shop. He claimed it was in perfect condition — which, unfortunately, it wasn’t.

A few weeks after we made the deal, it was time to pick it up. Since it wasn’t far from home, I rode it back myself. Almost immediately, I noticed play in the headstock bearings. Once home, I discovered I could nearly undo the main bolt by hand — it was practically falling out.

Not exactly confidence-inspiring.

That moment reminded me why I had started buying new bikes instead of used ones.

Still, I decided to establish a proper maintenance baseline and go through the bike thoroughly, replacing everything I deemed necessary.

---

What I Found

Here’s what turned up during the inspection:

• Headstock bearing play

• No coolant in the expansion tank

• Coolant leak at the water pump cover

• Leaking clutch slave cylinder

• Original air filter still installed from 2017

• Corroded battery terminals and a swollen battery

• Broken crankcase breather-to-airbox pipe

• Brake fluid in very poor condition

• Incorrect date set on the dash to avoid service warnings

• Missing toolkit

• Missing exhaust dB-killer

I dealt with the seller in good faith, but that’s what sometimes happens when you do. He largely refused any responsibility. In the end, I decided to swallow it and give the bike a fair chance. This wasn’t the bike’s fault — it was mine.

---

Rebuilding the Baseline

I started by disassembling the bike, beginning with the headstock bearings. Thankfully, they didn’t show any visible damage and the races were still in good condition. I cleaned everything thoroughly, applied a generous amount of grease, and reassembled it according to the KTM repair manual.

After reassembly, there was no play left. Mission accomplished.

Next up was the airbox. I opted for a UniFilter kit instead of a Rottweiler setup. To my surprise, the airbox was actually in good condition and not dusted — which is a known failure point on these bikes. At the same time, I replaced the crankcase breather and installed a new battery.

---

Accessories & Fixes

I removed a damaged Touratech phone holder that the previous owner had tried (and failed) to remove. In its place, I installed a Touratech nav bar with a DMD mounting plate for my RAM tablet holder, along with a 12V USB socket.

I also had to replace the lid of the small storage compartment on the right side — it wasn’t broken when I first viewed the bike. Since the toolkit was missing, I ordered a replacement.

The exhaust was missing its dB-killer as well. I managed to find a company that produces them, but delivery won’t be until January 2026. The same applies to the ABS/off-road dongle — also delayed until early 2026.

---

Mechanical Work Continues

I replaced the coolant and installed a new water pump cover, as the original paint was peeling. The cooling system was bled according to the manual and topped off again the next morning.

At some point, I’ll replace the oil as well, but I want to be sure there’s nothing else engine-related that needs attention first.

I continued cleaning the bike thoroughly, especially around the chain and sprocket area. After some research, I decided to switch to a 45-tooth rear sprocket, keeping the 17-tooth front sprocket.

---

Finishing Touches

To freshen things up visually and protect the bike, I installed:

• Frame protectors

• A Motopro Works sticker set for a more modern look

• Barkbusters with an aluminum brace

There’s still some work left to do. I already received the EVAP canister and SAS delete kits, but those will be installed later. For now, I want to ride the bike a bit and see how it behaves.

---

First Ride Impressions

I went out for a short two-hour ride last Sunday, and I have to say: that engine is an absolute peach. In Sport mode on slippery terrain it can be a handful — but the power delivery is addictive. I really love it.

All things considered, and given how I bought it, the bike now rides extremely well — certainly better than it did before I got my hands on it.

Next up: Motoz tyres, and then we’ll see how it performs off-road.

Bye for now 👊