LHM Change

[saintjamesy89]

Hello all, i'll be changing the LHM in the GT this week, along with the spheres. Got a few questions, how much fluid will the system need when drained, and how do I go about draining it? I've searched the forum but either didn't look hard enough or had a stupid moment!

[MULLEY]

There is a write up of the lhm change in the tech section somewhere, although it may not be available on the temporary forum as it currently is. Total lhm is about 5+ litres i believe when taking into account bleeding the brakes.

[Dollywobbler]

Draining isn't too tricky. Easier if the car is on ramps. Suspension in low, crack off the regulator so all fluid goes to reservoir. The tricky bit (depending on engine - a TD with a Bosch pump is very tricky, others can be a lot easier) is getting the tank out of its little corner. The metal clip is easily removed, then tilt until you can pull the filter head out. You may want a lot of rags at this point or put that little lot in a plastic bag - one that doesn't have holes in it). Beware of the very sharp edge on the inside of the opening. Also try not to slop LHM everywhere. With the reservoir out, you can now pour the LHM into a container. I like a 5l oil carton with the side cut out of it. Again, spillage is possible. Old oil can go to the tip.

Now you can remove the filters and clean them up using petrol. I use a brush to try and wash the muck away. Clean the reservoir (inside and out - don't forget the plastic disc at the bottom. Always has gunk underneath it and make sure it goes back in!), refit, refill with fluid. Some prim the pump by disconnecting the pump feed pipe, filling it with LHM then stuffing it onto the filter head. I tend not to. Either way, you're in for a bit of a wait now - how long is anyone's guess! Start the engine, tighten the regulator screw, suspension in high, cross your fingers and at some point in the next ten minutes, hopefully she'll rise up. Wiggling the steering can help, but you don't really want to do that on ramps.

For the full works, which is advisable, you need to bleed the entire braking system. Therefore it might be an idea to make sure all of the bleed nipples are going to play ball. You don't have to do this, so it isn't the end of the world if a nipple won't shift, but it makes a lot of sense with a car that's been sitting for so long - but if it goes wrong on the day, you don't have to panic. You can do the brake bleeding another day. I follow Haynes when it comes to bleeding the brakes. I might do it on the TXD as the brakes are rubbish by BX standards.

[MULLEY]

Its amazing how much crap is usually in the bottom of the lhm tank reservoir underneath the disc. The brakes also usually contain very old lhm that is usually a yellow piss colour along with brown debris that builds up as they are dead stops. Doing the full change is much better than the easier method, it does take more time though, & watch out for the bleed nipples, they may be jammed in solid. I get a wire brush on them to clean them up, & then get some plus gas onto them in readyness for doing the lhm change. I then use a 5 sided ratchet & gently start to put some pressure on it & when it starts to move, i re-tighten it up & then get it turning a bit more than last time whilst adding plus gas to the bottom of the threads when its moved out a bit each time. If you do this proceedure they should come out. If you find the bleed nipple starting to round off, stop immediately, i usually use a hammer & belt the side of the caliper near to the bleed nipple to shock it & then use mole grips & start moving the bleed nipple backwards & forwards. If that doesn't work its seized in & you'll need to get a replacement caliper fitted. Thats why i find checking the bleed nipples the week before doing the lhm change, incase you need to get a caliper as part of the lhm change. Best of luck, i managed to free off 3 of Mickey's, one refused to budge much & started to twist & would have snapped off, so i just gently re-tightened it to stop the lhm from coming out & left it alone. The molegrips do damage the top of the bleed nipple, so i'd factor in buying some replacements, not cheap though

[Dollywobbler]

I was AMAZED to get a bleed nipple moving using the technique Mulley suggests. Gently back and forth, with a squirt of penetrating oil (proper penetrating oil) here and there. Use any force and the thing will just snap - or that's the impression I got. I actually ended up hammering a 7mm spanner onto the bleed nipple. The shock on the nipple probably helped too - but probably best to clout the caliper rather than the nipple!

[mat_fenwick]

Old oil can go t?o? ?t?h?e? ?t?i?p? in your fuel tank.

Edited for accuracy...

I might do it on the TXD as the brakes are rubbish by BX standards.

Does it have ABS?

[Dollywobbler]

Nope.

[saintjamesy89]

Thanks for the advice chaps, with all this info it should be plain sailing I even got the rear two bleed nipples off last year when I was playing with the brakes - as to the fronts, I don't know yet (Thanks for the bashing tips Mulley, hopefully they'll not be needed though!). I do plan on doing the whole kaboosh while i'm at it. With the LHM tank, I think it should be fairly ok to get out as i've removed all of the cambelt casing stuff.

When you say crack off the regulator Ian, do you mean the bleed valve thing that you use to depressurise the system (as when doing a sphere change)? Also, what is the purpose of the ramps? I don't have any, and the garage the GT's in is quite narrow making it awkward to get any anything anywhere.

Mat, you can run a car on LHM? Is it ok for the engine?

[MULLEY]

Yeah, ian meant depressurise the system as per sphere change, it makes more lhm go back into the tank, the car needs to be on axle stands as you also need to put the suspension in its lowest setting to ensure as much of the old lhm goes into the tank as well as taking off all 4 wheels to access the brakes (if you are doing the better method, if not then you don't bleed the brakes so can keep the wheels on, but you'll need sufficient access underneath to get at the bleed valve screw). It only needs to be turned a little bit, 1/4 to 1/3 of a turn, you'll hear a wooshing sound, thats it de-pressurising.

Erm do you mean instead of engine oil? i wouldn't as its not designed for engines & its a damn site more expensive per litre than oil. Engine oil is designed to run at high temps, lhm isn't.

[mat_fenwick]

An older diesel engine like ours will generally run OK on a range of oily stuff, although I wouldn't run it on 100% LHM. Up until around 40k miles ago I used to put 2-3 litres of old engine oil at a time into the tank after an oil change. (Pour the lot in and it gets a little smoky!) The reason I stopped is only because the fuel gauge sender got clogged up with it. There seems to have been no long term ill effects though, and LHM is/should be a lot cleaner than used diesel engine oil.

[MULLEY]

I used to put old engine oil into my fuel tank as well, but found it eventually clogs up the fuel filter, so does it really save any money longterm? The most i used was 2 litres in one tank of fuel, plenty of smoke which i found handy for those tailgaters, but i've not done it recently though.

[Tim Leech]

Getting the lhm tank out of a carb fed petrol is quite easy as theres plenty of space. Have plenty of cloths standing buy, you cant overfil it tom as it just overflows if you do. Even ive done it!.

[mat_fenwick]

found it eventually clogs up the fuel filter, so does it really save any money longterm? The most i used was 2 litres in one tank of fuel, plenty of smoke

Certainly the filter goes black straight away, but haven't experienced actual clogging - i.e. restriction of flow under high fuel demand - between 15k mile filter changes. It was partly to actually get rid of the stuff, to save a special trip to dispose of it. I really couldn't detect any extra smoke with 3 litres in a full tank, but then I may be putting out more smoke anyway...

As to the effect on engine life, I can't really say whether used engine oil has knocked (say) 20k miles off the life of the pump. But it certainly hasn't caused any instant harm and I'd be even less worried about LHM. Or you could just use it to start a fire

[MULLEY]

I'd say used engine oil in the fuel tank was actually good for the diesel pump, it'll provide a bit of extra lubrication which i can't see harming anything.

[citronut]

Getting the lhm tank out of a carb fed petrol is quite east

naaa naa Tim its West at least in my engine bay it is, and om sure it were in Gloria's also

regards malcolm