Engine rebuild part

[jvbram]

Hello. Just bought a well maintained 1991 TD in SW france near where i live. Its done 350k and can be slow to start. I think the compression is down. So i would like to rebuild ghe engine. Does it have piston liners? Where can i buy them in UK? I recently did a Mitzy 4D56 engine using a complete rebuild kit from the UK.

[white exec]

Hi,
How are the glow-plugs and glow-plug relay? These engines can be difficult to start with even one or two not working.
What's a hot start like?
Most unusual for pistons etc to need renewal, even at 500,000 miles. Is your 350k miles or km?

Our '92 BX is ex-Nice/Marseille (Aubagne).

[Kitch]

They don't use liners, it's an iron block. You just re-hone the bores in the block itself.

[jvbram]

Chris, thanks for the tip on the glow plugs. I will check it out. Its done 350k km. Runs and performs well Doesnt burn oil but may not pass the emmissions test. Dont know what the test is called but the tester jumps on the pedal from idle and revs it up tp 4000 rpm. Some grey smoke can be seen. I think its because there the turbo lags the fuel injection. Or the fuel air valve that sits on top of the injector pump is too generous too soon. When it has caught up there is no smoke. Good thing about old cars from occitane france is often no rust!

[jvbram]

In that case Kitch, can you get oversize pistons?

[white exec]

From what you describe, the engine is in good condition, and behaving normally.
Booting the accelerator for the Test is just the prescribed way of checking for excessive emissions (smoke) under heavy throttle. Over-fuelling would send out lots of black smoke, which you don't seem to be getting.

You can get an idea of the evenness of compression by cranking a warmed-up engine for 5-10 secs without letting it start*, and listening to each compression stroke. They should all sound the same. If there is any significant leakage past a piston or valve, you'll hear a momentary acceleration of the cranking as the leakage offers less resistance.

* Prevent from starting by disconnecting the single wire from the stop solenoid on the injection pump, or by holding the pump's stop lever over.

[rutter123]

Check the turbo for wear on the journel bearings.

[jvbram]

I have the head off now and some of the valves leak. Pistons and bores look ok. What compression should it get? At what pressure should the injectors open?

[white exec]

Haynes lists compression pressure (engine hot, cranking speed) as 18bar minimum.
Normal range 25-30bar.
Max difference between any two cylinders, 5bar.

and Injector opening pressure
Roto-Diesel 115 ± 5bar
Bosch 130 ± 5bar.

[Kaapelimies]

Now when you have the head off, measure that all the pistons protrude same amount over the block, the correct measurement is in Haynes. I would recall it's around 0.8mm and the difference between pistons should not exceed 0.05mm or so. I had one BX D that had snapped the cam belt, one of the pistons was level with the block, and when dismantled the connecting rod was so twisted it was easy to see by naked eye. And it was only 0.8mm in length difference..

[jvbram]

Thanks Chris and Kaap. While i have you, is the accumulator sphere the same as the other four?

[white exec]

The accumulator sphere is different: no damper in the neck (just a 5mm hole) and gas pressure of 62bar.
Needs to be correct.

[jvbram]

Putting it back together now. On the thermostat there is a 10mm hose barb on the side facing the fuel injector. what does that connect to?

[white exec]

Coolant expansion tank, if I remember rightly.
The 'stat housing is a high point on the system, so it is an expansion/air-bleed point, and to prevent air accumulating around the 'stat and temperature sensors.

[jvbram]

Nup. There is a smaller pipe that goes from the front of the thermostat housing to the bottom of the expansion tank. When i fill the cooling system water (cold) pours out this spur on the opposite side of the thermostat housing to the tank. This is a major artery. There is spur on the head under the right lifting lug but that hose goes to the cold start accelerator. Ive got the diesel version of Haynes but no schematic of the hoses. It doesnt look like turbo is water cooled. Next time you pop the bonnet on the Exec can you have s look for me?