Aftermarket exhaust systems often put a lot of stress on turbo and manifold gaskets because they add extra weight and are much more rigid than the small diameter factory piping.

Hard use, especially on the track, can shorten turbo gasket life to hours!

This exhaust already had an ugly join where smaller diameter pipe had been used to lengthen it in the past, so I was able to cut that section out and replace it with a stainless steel flex joint. This should allow the rear half of the exhaust to move a bit without levering on the turbo.

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 a bit of a history of overheating.

It was taken to a workshop and had the head gasket replaced, but it continued to overheat. The workshop kept fixing the symptoms (blown hoses, etc) but not the cause!

By the time I saw it the head gasket was leaking badly and it was most likely that the head was damaged - making another head gasket replacement unlikely to be successful.

I sourced a replacement engine with half the k’s on it and swapped it over.

After a service, a bit of a tune and a general checkup the new engine was running nicely - and no more overheating!

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!

This started out as a routine checkup of an Evinrude / Johnson 90hp outboard motor about to be put into use on a boat, until someone gave it a compression check and found one cylinder to be reading low - deciding it was in need of a rebuild.

I like to avoid rebuilds and other such expensive activities where possible, so thought it’d be worth seeing if the engine would run first.

After connecting up a fuel tank and battery it started up quite easily and seemed to run ok. After a brief run I gave it a compression test and found that three cylinders had a healthy 120psi, but one was down to about 70 - which is low, but not completely dead.

The head gasket was leaking a bit of water, as it had been removed previously and not re sealed, which may also have contributed to the low compression reading.

I pulled the cylinder head off to have a look inside and re seal the head gasket and found that the engine had obviously sucked something solid through it and munched the piston and head fairly extensively!

The piston obvously has had a hard time, but the cylinder walls actually looked ok. The most likely cause is that the engine has sucked a nut or washer through at some point.

The cylinder head was in a similar state to the piston, but it’s a lot easier to tidy up, so I was able to flatten out most of the sharp points.

I cleaned up the sharp edges on the piston as much as possible, then applied high temperature sealant to the head gasket and bolted it back together.

The engine fired up and ran quite smoothly with no more water leaks.

Another compression test showed compression on the bad cylinder to be up to about 90psi, so the engine will be used at least to test out the boat and decide whether it’s the right size, etc before spending big money on replacing or rebuilding it.

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!