This car was already running an aftermarket air filter with a heat shield partition that sealed against the bonnet when closed - but having a full cover makes it street legal and avoids hassles.

It’s made from 1.6mm aluminium sheet, and attaches to the existing partition and a headlight bolt. There is also a hole for the air filter mounting, replacing the original bracket.

Here’s a photo from a nice angle. The Silvia on the left is waiting for an engine and a few other jobs, and will hopefully be on the road soon!

A blown head gasket is usually a pretty big deal, and generally happens due to excessive overheating or other engine problems.

This one was a bit different - because the engine was leaking coolant from the join between the head and the block, but had no other blown head gasket symptoms!
There’s no real way to fix it without replacing the head gasket though, which is a fairly big job.

After removing the head and gasket, it was obvious why it was leaking. A small crack was letting water from the cooling passages out to the side of the engine:

The cylinder head was sent off for machining (to make sure the sealing surfaces are perfectly flat) and cleaning. In the mean time, the block was cleaned up. It’s important to remove all traces of the old head gasket, sealant, and corrosion. I also cleaned the carbon that was built up on the pistons.

While the engine was apart, all the rubber hoses (now 20 years old) were replaced with new silicone ones to ensure future reliability. The heater hoses are a common problem on the CA18 engine.

The water pump and timing belt were also replaced while it was apart, so there should be nothing much to do for another 100,000km or so.

This car had recently suffered a major increase in fuel consumption according to its owner.

The usual complaint of “only getting 300k’s to a tank” is often caused by a failed or failing oxygen sensor (O2 sensor) which monitors the exhaust gases to allow the engine computer (ECU) to control the amount of fuel to give the engine.

O2 sensors often last less than 100000km, and are not particularly expensive or difficult to replace.

I did a quick test on this one to see if it was working at all, by connected an oscilloscope to the sensor output and monitoring the signal while running the engine.

As can be seen in the photo, the signal is waving up and down, which shows that the ECU is controlling the fuel mixture based on the sensor signal.

So the sensor is working, but it is possible that the sensor’s output is not accurate, or even that the connection was faulty and inspecting it has made it work again.

I’ll keep an eye on this car and do some more tests if the fuel economy doesn’t improve.

This one was pretty quick, just swapping a noisy and leaky power steering pump for a good one.

It was making some pretty bad noises, easily mistaken for serious engine trouble!

Swapping the power steering pump is fairly straight forward, apart from the ridiculously tight banjo bolt holding the pressure hose on.

It’s also a good idea to flush out the old fluid and refill the system with fresh stuff.

This car had the usual blown turbo gasket problem, and the owner figured it was a good time to upgrade the turbo to a newer T28 ball bearing one from a Japanese spec S15 Silvia.

The leaking gaskets are usually caused by the exhaust hitting the ground, or not being properly supported when the factory exhaust is swapped for an aftermaket one.

In this case there was a broken stud in the head, causing the manifold gasket to leak, as well as the normal leak between the manifold and turbo.

Removing the stud involved drilling a hole into the part still stuck in the engine, then using an extractor tool to unscrew it. A new stud was then installed.

Upon inspection, the new T28 turbo proved to have substantial damage, having obviously been in a crashed car. The compressor housing had been broken and pushed back into the blades, damaging them beyond repair.

Fortunately the original T25G turbo checked out fine, so it was reinstalled - after removing a broken bolt from the turbine housing!

Today I replaced a bunch of turbo gaskets, installed braided flexible coolant and oil lines, fixed up some vacuum plumbing and installed a boost controller in a Nissan 200SX (Silvia).

The turbo gasket had blown, which often happens when people run an aftermarket exhaust which isn’t supported properly. The extra weight and missing bracket in the middle puts a lot of stress on the turbo mounting bolts and they tend to loosen off.

This starts the gasket leaking, and eventually it burns through and leaves the turbo hanging loose, dropping performance and making a loud exhaust leak sound.

While the turbo is loose and able to move around the metal coolant and oil pipes are constantly flexing, and they eventually crack and you have a coolant leak as well as an exhaust leak!

So, a new set of gaskets, replacing some damaged manifold studs (and retapping the thread in the engine!), a set of braided lines, and it was good as new

Another problem this car had was that the boost control solenoid was hooked up to the wrong vacuum line, which meant the boost control system didn’t work properly, causing overboosting.

That was fixed up and a new boost controller installed, allowing in cabin adjustment.

Unfortunately I didn’t get a chance to take some photos!