2.1 Diesel Pre-heater Leak, and its not air in my diesel!

The pre heater on the side of the block, known for letting air into the diesel and causing poor early morning starts, has gone the other way, its letting water out!

It may just be the plastic piece that joins it to the rubber pipe, but either way its annoying.

Does anyone know if it can be got off easily, or can I expect to put 2 days to one side for it..........


Found this while investigating a squeel, thought it was just the alternator/belt

As I remember it the heater has no connection with the water, its just bolted on to the end of the cylinder head, unless the water is leaking out of one of the bolt holes.

Peter.N.

Hi Lez,

The preheater is a block of aluminium casting which is bolted to the side of the cylinder head covering a large hole. The outer perimeter of the block has a fibre gasket to seal it to the cylinder head. The hole inthe side of the cylinder head allows the circulating water to directly contact the back of the pre-heater block.

Where is the leak coming from? The most likely place is around the gasket. For it to leak out of the fuel side the aluminium block would have to be porous to water and allow water to pass through the two skins of the block.

I have my own theories about the block itself. I know it gets bad press for being porous and nearly every car has it bypassed. However, the last time I took mine off the head I pressure tested it and found that the block itself was OK. The leak was coming from the plastic thermostatic device which is pressed into the block. The thermostatic device only allows a proportion of the fuel to be preheated and blends it with fuel sailing straight past. The injector pump therefore sees the blended temperature. Temperature control therefore is achieved by varying the proportion of heated fuel to bypassed fuel. I'm thinking the problem is more likely to be the aluminium plastic interface and not the block itself. The symptoms and the solution are however the same. I've never had a spare one since to do any further investigation on.

cheers

noz

Mine has a plastic pipe attached to it, I'll go take a picture now, hang on.........

grr, cant link the image, dynamic amges are not allowe d blah balh vlahfSFLKADSJFLKSDJFGSD
GFSD


http://f7.yahoofs.com/users/45910199m48323...hIyfwFBpT67G5d6

As you can see, plastic pipe, attached to pre-heater, water passes from block, through preheater, into plastic pipe.

You can see the orange rusty marks in the area from water and my orange antifreeze.


This post has been edited by lez on February 01, 2007 03:12 pm

Metal does not go porous, IMHO, I have had 2 leakers, both fixed the same way, the pipes that carry diesel in/out are not an issue, its the thermostat 'device' just behind them, seems to be held in by by a metal spring washer and seal, when its on the car, you can see it from above.

Filling the area with my old friend sillicone sealent fixes it fine, you get warm diesel and no air....

Hi lez,

I think, (I hope) I said the same thing !!

Am I alone or does your link lead to a dead end?

Cheers

noz

>Am I alone or does your link lead to a dead end?


Err, does now, didnt when I posted it, and its my yahoo photos account so /should/ always work...........

I'll start an immediate investigation...

http://uk.pg.photos.yahoo.com/ph/lez_bridd...re2.jpg&.src=ph


This post has been edited by lez on February 02, 2007 11:01 pm

Sorry Noz, you are right, as I would expect. I dont know whether its failing memory or just because I havn't had one off for a long time. Now I know why mine is still bolted to the head even though it has nothing connected to it.

Peter.N.

just to add a bit to this, my pre heater was not leaking, it was apipe spurting water onto it and then dripping off, silliy me........

as to letting air in, they fail above the top pipe connection, you can see a round indented area with something in it, that 'it'has a matal spring clip/washer that corrodes and fails, just fill the area with some sealent, and you can have a working pre-heater again.