Engine Coolant Loss / Overheating

Hi All,

I've trawled LZ for about a week trying to find my specific issues and identify possible solutions but frankly I'm at a bit of a loss.

My car:

• Defender 110 300 TDI M Reg

My Issues:

1. I've been losing engine coolant for a few weeks now having noticed my heating wasn't working properly. It's not a huge amount (header tank per week) but still annoyingly frequent! We identified a small leak around the water pump gasket so put in some K-Seal to try and seal it short term. However I'm still having to top it up once a week.
2. Every so often after starting her up in the morning and heading off to work, I've noticed the temp gauge going over halfway and sometimes further. I stop, give it a minute and restart and it settles back to normal for the rest of the day. When this happens, I notice the heater is also blowing cold!
3. It also feels a bit lumpy just as I'm stopping at, for example, a roundabout or traffic lights but then settles down again and ticks over ok.
4. It has also been struggling to start now it's cold! Usually takes 2 or 3 goes!

I'm hoping it is "only" a water pump replacement but not hoping it is a head gasket problem!

Anyone had any similar issues/experiences?

Cheers,

Mo

If the head gasket was leaking into the cooling system you might get bubbles in the header tank when running - worth a look. Sounds like you have already found the fault though. Even a small leak at idle can lose a fair bit of water on a run.

The heater blowing cold is the first sign of coolant loss as it is the highest thing in the engine bay.Top up often and fix soon before you suffer a major loss and possible engine damage.The temp gauge is NOT a good indicator of coolant loss as once the level drops below the level of its sender the reading will drop and will only rise again when whats remaining of the coolant turns to steam,at this point damage is likely.

Have you rebled the system properly? They're a little infamous for air locks.

zeaphod said:

If the head gasket was leaking into the cooling system you might get bubbles in the header tank when running - worth a look. Sounds like you have already found the fault though. Even a small leak at idle can lose a fair bit of water on a run.

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Thanks, I'll check that later!

tottot said:

The heater blowing cold is the first sign of coolant loss as it is the highest thing in the engine bay.Top up often and fix soon before you suffer a major loss and possible engine damage.The temp gauge is NOT a good indicator of coolant loss as once the level drops below the level of its sender the reading will drop and will only rise again when whats remaining of the coolant turns to steam,at this point damage is likely.

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Thanks. Yes I should check before I leave! Can't understand though why the gauge goes back to normal and the heating works again. Could it be an airlock?

blue beasty said:

Have you rebled the system properly? They're a little infamous for air locks.

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Thanks. Not sure! it could explain why the heater doesn't work and then works again after I switch her off and on! I'll have a look!

Could well be an air lock because if coolant is getting out air can get in.

personally, i'd keep away from kseal and others.. if they block your narrow waterways or rad.. it'll hurt.

i'd look at airlock as above re temp gauge and cold blower.

hard cold starting and faltering at roundabout.. i'm presuming it's not run on veg. i'd look at lift pump and also check your glowplugs work.

Check you 'P' gasket isn't leaking, look for a rusty stain on the block by the alternator. If it leaks then the heat of the block evaporates the water so you don't actually see the leak. Look here. You can also ask a garage to do a 'sniff test', that will see if there are any exhaust fumes in the coolant which is a sure sign of a head gasket leak.

Ok, topped it up to the header tank level, drove around for a bit and noticed the heating wasn't coming on.

Parked up with the engine running and removed the header tank cap (it hissed and some coolant came out) and the level had dropped by half an inch. There were bubbles in it but it wasn't bubbling while idling.

Turned it off for a bit and then headed back to work and although the temp gauge was near half way, no heat. Then a bit later the heater was working!

Got back to work and checked for bubbles again; nothing.

Any further thoughts!

Replace the gasket you know is faulty, flush the system well, refill with antifreeze mix and try again - might need some bleeding but ought to come right - good luck.

ps. while you're about it test/replace thermostat.................................

waldamar said:

Replace the gasket you know is faulty, flush the system well, refill with antifreeze mix and try again - might need some bleeding but ought to come right - good luck.

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And if you are going to replace the head gasket then check the head for warpage and cracks and skim or replace as necessary. Replacing the gasket without doing the checks may cure things for a short time if it is warped or it will be the same if cracked. Do it right and do it once.

Thanks to all that have responded!

I'm going to get the P gasket replaced as it is definitely leaking. lots of orange stuff on the casings as per the pics; thanks Kwakerman!

One other issue I forgot to mention was that it billows out lots of white smoke when idling and pulling away. The thing is, it doesn't do it every day!

And I do seem to be burning more diesel than usual! Lift pump?

What they said..... replace P gasket first and see how it goes. If it remains the same, it's head-off time (the white smoke is indicative of head gasket failure, or worse, a cracked heaad). Don't let the job daunt you. It's not difficult by any means. Removing it shouldn't take longer than 2-3 hours if you take your time. Add another hour to dismantle it fully and allow as much time as you can to clean everything up really well. If your head isn't cracked and is still straight (I'd still recommend a very mild skim at a machine shop), treat the valves to a good clean and a good lapping-in, change valve stem seals, service the injectors and pop the head back on. The job can be done in a longish day but only if you're not skimming the head or servicing the injectors.

If its loosing coolant and blowing out "smoke" then that sounds like head gasket failure to me.

But the others are easier to do first.

A nice tip that someone showed me was -

When refilling the headder, make a funnel out of the top of a 2ltr coke bottle. This allows you to get a 'head' on the headder, and makes bleeding a whole load easier.

Thanks reiny.

The thing is, it doesn't happen all of the time. If it were a HG failure, wouldn't it be constant?

Not always - it's a funny old world................. it'll leak a bit, temp changes, seals itself a bit, seems better etc. It's amazing how bad a HG can get and the motor still run/drive. I fear it's early stages - sorry..................

Thought you might say that

Other than taking then head off, is there a way of testing for HG failure?