Melted Thermostat Housing Bung or Blown Head Gasket ?

[merlin]

My TDi 300 (160,000km) is currently in the reapir shop after loosing its cool on a recent road trip. When I popped the hood I found that the newly replaced Thermostat Housing Bung (Black Plastic Bung) had sheared off and looked pretty much melted.

The repairer has just told me that the Head Gasket looks like it was leaking for the past 6 months or so, and has probably just let go all of a sudden.
I did not notice any pressure build up in the Cooling system, or any increase in the temperature.

The repairer also said that this is a common problem with TDi's !!!

I have never heard this before, What are your experiences ?

Merlin :cry:

[JamesH]

I've heard they hate to get cooked. The head often warps and they do gaskets.

I was told that whatever I do with mine, keep the cooling system in top nick and check levels etc. And when they do get hot or lose fluid, stop.

Hope it turns out OK.

[p38arover]

My local Landie repairer replaces the plastic bungs with brass ones.

Ron

[spudboy]

I had the same leak by the sounds of it. Brass "disk" plug half way down the main engine block was leaking coolant, but just slowly (it didn't make any puddles on the drive or anything).

The mechanic said there is a design fault in the temperature gauge sender on a TDi300, such that if the fluid level drops, the sender is only in air, so you don't get a warning on the dashboard that the engine is overheating.

Before you know it - head warped. $1600 repair bill. Damn.

To test for a leak, they filled up the coolant to the very top, and watched for a minute or two with the lid off, while the engine was idling. Every 30 seconds or so, a belch of air would come backwards through the coolant.

[p38arover]

Originally posted by spudboy
Brass "disk" plug half way down the main engine block was leaking coolant,.

That's sometimes called a freeze or core plug by Americans and a Welch plug here.

Ron

[merlin]

Hi Spudboy

I live in the Adelaide Hills as well
I used to get the Landrover serviced by Ian Lennox but he had an accident and does not do any work anymore

Where do you get your Landie serviced ?

Merlin

[one_iota]

Ok FWIW

Experience:

Cooked engine on a trip from Sydney to Melbourne. No warning apart from a hestition in the engine and then noticed the temperature needle in the red and the smell of coolant. Stop the Disco and no restart. Water levels seemed ok but that was the level in the header tank. Tray back to Sydney and scored cylinder due to over heating. Rebuilt the donk.That was 120000 km ago. Cost $9k

Another occasion the plastic fantastic plug failed: smell of coolant and being winter no heating. Brass plugs installed.


Anecdotes:

The temp sender is not an indication of the well being of the system: Install a low level coolant alarm.

The heads on some Tdi's weren't screwed down to the correct torque settings.

Aluminium head warps so this needs to be checked if over heating occurs.

[barryj]

Originally posted by merlin
My TDi 300 (160,000km) Thermostat Housing Bung (Black Plastic Bung) had sheared off and looked pretty much melted.

Get rid of those plastic plugs and replace them with brass or bronze. From what I remember there is one in the radiator as well. Any mechanic with experience with rovers should know this.

I have heard first hand from a guy who lost $10,000 when his went.

[merlin]

Thanks Everyone for your replies

I too had absolutely no warning at all of an overheated engine

We just pulled into our usual halfway stop and I noticed that I had no power steering looked at the gauges and noticed that the engine had stalled and then the tell tale steam comming from the bonnet !!!

It looks like a $2.00 Plastic Plug is about to cost me $4,000 in repairs if the Head is OK, otherwise could be $6,000

Merlin

[Bushie]

Not sure about the 300Tdis but its a good idea to keep an eye on the radiator water level (at the rad) as well as through the header. Apparently its not unknown for the radiator to get dangerously low while still having what appears to be plenty of water in the header.



Bushie

[merlin]

Originally posted by barryj+--><div class='quotetop'>QUOTE(barryj)</div><div class='quotemain'><!--QuoteBegin-merlin
My TDi 300 (160,000km) Thermostat Housing Bung (Black Plastic Bung) had sheared off and looked pretty much melted.

Get rid of those plastic plugs and replace them with brass or bronze. From what I remember there is one in the radiator as well. Any mechanic with experience with rovers should know this.[/b][/quote]

The funny thing is that they replaced the old Bung with a Brass one, which leaked a little, and I asked them to toghten it up, and they replaced it with a Genuine Plastic Bung, and then the trouble started

Merlin

[kie4]

Hi Thermostats in the 300 tdi are rubbish in hot conditions what you need to do is cut the centre out of the thermostat , just leaving the outer ring for the rubber seal.
VERY IMPORTANT you need to insert something like what's in the picture below ( from v8 clutch fork assembly ) into the water hose that is at the top of the engine from the thermostat housing that arches over and goes to the water pump ( this water pipe is required for rapid warm up of the engine if a thermostat is fitted, not required if thermostat has been removed) once the engine is warn the thermostat cuts the flow through this pipe anyway.
You will no longer have overheating problems on your 300 tdi.
this procedure has been tried and tested very successfully in all our safari hire vehicles in Africa.
We hardly get any overheating engines now, after years of expensive head/engine replacements.
We also carry out this procedure to vehicles we prep to travel through Africa.
and do what everyone else is saying " get rid of the plastic bungs"
If anyone needs more info on this please let me know https://www.aulro.com/afvb/*

[kie4]

Help I cant attatch photo
how do you do it ?

[DEFENDERZOOK]

[quote=merlin]<span style="color:green">We just pulled into our usual halfway stop and I noticed that I had no power steering looked at the gauges and noticed that the engine had stalled and then the tell tale steam comming from the bonnet !!!

Merlin</span>


[b]<span style="color:blue">must be one very quiet and smooth running diesel engine.......</span>




[quote=kie4]<span style="color:brown">Help I cant attatch photo
how do you do it ?</span>


<span style="color:blue">right click on the pic if it is located on the internet......
or if its on your hard drive....up load it to an album.....

after you right click on it.....go to properties and hi-light the url address....
copy and paste it in your post.....

now hi-light it and then click on the img button at the top of your text box...

and when you click submit you should have a photo......</span>

[kie4]

file:///Users/richardmackie/Desktop/Desktop-Images/0.jpg

[spudboy]

Hi Merlin - I live at Balhannah growing grapes. Where are you?

I had 1 service done by Black Forest Land Rover, for which they tried to charge me $650. I told them to shove it and we eventually agreed on $400. Never need to go back there luckily.

Since then I have always gone to Soverign Motors (down in Adelaide). They use genuine parts and have an ex-UK Land Rover mechanic who is excellent. Would highly recommend them.

[barryj]

[b]<span style="color:blue">must be one very quiet and smooth running diesel engine.......</span>



It's never been so quiet as it is now......... :oops:

[Bushie]

Originally posted by kie4
Help I cant attatch photo
how do you do it ?


Have a look through this thread

http://www.aulro.com/modules.php?name=Foru...highlight=paste (http://www.aulro.com/modules.php?name=Forums&file=viewtopic&t=5047&highlight=paste)



Bushie

[Grizzly_Adams]

Originally posted by kie4
file:///Users/richardmackie/Desktop/Desktop-Images/0.jpg

Unfortunately that was still on your local disk.

You need to upload it to a website somewhere and link to it. Can be any website, even this one! Just create a gallery and link to it there.

Else send it to me via email and I'll put it up for you.

Cheers,


Glenn.

[George130]

kie4 does this mod work with the TD5. Had the pressure test done on mine today and it seemed fine 8) . Tomorrow I will be having the chemical test of the coolant (Currently water) done. If my head is ok I am talking to a local garrage about the cost of building a custom thermostat housing to accept the common ford/holden ones so I can change it at will. We are also looking into the work involved with replacing the hoses with metal ones with small rubber joiner bits.

[merlin]

Hi Spud Boy

I live in Littlehampton
Work at UniSA in the City
Wife works in Woodside and takes the Disco with her, so we found a Diesel mechanic in Woodside but I am not sure of their knowledge about LandRovers

Merlin

[merlin]

I imagine that it is pretty standard for a Diesel

However I was in a cross wind, towing a horse float (No Horse), with three kids watching Harry Potter on DVD, (Great distraction for the kids on long trips)

Well that's my excuse... and Iam sticking to it...!

Merlin

[Grizzly_Adams]

ok here's the pic of the Thermostat mod:

http://www.aulro.com/albums/album339/Thermostat_mod.jpg

[DEFENDERZOOK]

<span style="color:blue">now im confused....


that pic looks nothing like a thermostat.....or a mod....


is that the blanking plug that is to go into the hose mentioned by kie4...?


someone please help me..... </span>8O

[Grizzly_Adams]

Hopefully kie4 will shed some light on the situation. I just posted the photo he sent me https://www.aulro.com/afvb/

[kie4]

hi yes that is the plug you put in the top hose

[Andrewpv01]

Kie4,
I have always been told that removing the thermostat stops the cooling system from working properly (although I have done it).
I though that the coolant would then flow through the radiator too fast to cool properly, or are you describing something different?

Andrew

[incisor]

you should only cut the center of the thermostat and put the outer ring back in as the restriction creates the pressure to wash the coolant right thru the block.

[kie4]

hi andrew , A thermostrat is put in the cooling system to aid rapid warm up of the engine.
most of the wear in an engine happens when the engine is cold.
as for the coolant going round the engine to fast, thats goverened by the water pump.
to answer incisor , you dont need a thermostat to create a restriction to wash coolant through the block, the water pump pumps the water round the block

[rick130]

Personally, I would never run any engine without an operating thermostat.

Why ?

Removing the thermostat is a band-aid solution (and IMHO, a poor one at that) for a cooling system problem.

Firstly, as has been stated, the thermostat aids in quickly warming an engine up to running tamperature.

Secondly, every engine, particularly diesels, have an optimum temperature at which it is most efficient/produces optimal power/least wear. In my experience, this is in the 90-95*C coolant temperature region (this includes racing engines !). This is the temp where all the operating clearances are optimal, and combustion is at its most efficient. Remember that power is synonymous with heat. Internal combustion engines are very inefficient. The heat of the expanding gases is what powers the piston back down the bore. Far too little of this heat is used for this. The vast majority disapears into the cooling system and out the exhaust (at least the tubocharger turbine harnesses some of this)
Too low combustion chamber temperature provides insufficient burn, leading to reduced power and unburnt fuel going out the exhaust. A diesel is a compression ignition engine. This means that very hot air ignites the fuel when it is injected int the combustion chamber. Not as hot as it should/could be leads to incomplete combustion, which equates to loss of power, increased fuel consumption, higher exhaust gas temperatures and increased wear.

Thirdly, I believe that most engines need a certain amount of restriction or back pressure, generally accorded by the thermostat for optimum coolant flow through the block/head. It was fairly common years ago to see irregular bore wear in Holden sixes after extended use without a thermostat.

If an engine is overheating, please don't take the (seemingly) quick fix option of removing the thermostat. Please take a holistic approach and look at the overall system. It may be a lack of airflow, (remember that the superheted air from the radiator has to exit the engine bay for ambient air to flow through the radiator. This often isn't properly addressed) perhaps the pump lacks sufficient volume, the heat exchanger (radiator) lacks surface area, the exhaust system may have a restriction, or it may be as simple as the type of coolant used can be optimised. (e.g. OAT coolants have a heat transfer co-efficient roughly half way between conventional ethylene glycols and pure water)

A thermostat is only a temperature regulator, nothing more, nothing less, but it is an important job, and not one that should be eliminated lightly.

[cookiesa]

After having bought a 300Tdi through Blackforest. Harmonic balancer wasn't tensioned properly, then the engine overheated. After much arguing and about 3 months without our car the vehicle was picked up, brought back to whyalla and the water pump and bung in the side of block was leaking. Local Natrad replaced with brass ones and fixed the leaks at there expense but would not buy a T-Shirt from this lot. (The dealer principal not once responded to my emails to them or called. Too busy hiding behind his staff)

Have since fitted a coolant alarm. Good invistment IMHO.

Have been happy with all the help and service (paid and unpaid) I have recieved from Lynda's Landrover's They are down the road opposite the Parafield Airport Gates.

Ex Army mechanic. The younger mechanic that works there is also very good and they are straight up. Great help sourcing parts when they don't have them.

[cookiesa]

For those who aren't aware prestige at walkerville is the same owner. Amazing Land rover are happy to have people like this represent them.

The previous owner of my vehicle when I contacted them won't deal with them again either.

[kie4]

rick 130
A 300 tdi has a problem with overheating caused by the thermostat not opening, exaggerated in hot climates.
removal of the thermostat does not lower the coolant temperature but does slow down the rate of which the temperature rises.
the reduction in power if any will not be noticed in a landrover 300 tdi it isnt a performance vehicle.
your third point is a contradiction, you say the engine needs a certain amount of restriction for optimum coolant flow, you cant restrict something to get the optimum out of it!!
you are correct in saying check air flow and possible radiator blockage , but a restriction in the exhaust will cause power loss not overheating, and as for the type of coolant used ‘its a landrover&#96;
as you also say a thermostat is only a temperature regulator nothing else, but if its not working due to the design of the engine take it out and save yourself hundreds of dollars !
As I said in my first post it has been tried and tested very successfully in African temperatures.
My 300 tdi has been to cape town and back through temperatures you wouldnt believe,
its now clocked up 175000 miles, with its original head gasket.
It passes its MOT emissions test each year which are pretty strict with no problem ( with the ERG valve removed(another thing you dont need)
Im not saying to people to remove their thermostats in any other engine but its a bloody good “band aid” for a 300 tdi

[incisor]

Originally posted by kie4
your third point is a contradiction, you say the engine needs a certain amount of restriction for optimum coolant flow, you cant restrict something to get the optimum out of it!!
fluid dynamics... he doesnt mean it in terms of gallons per hour he means it in terms of the coolant flowing thru all parts of the block. with out the restriction of the thermostat aperture the coolant takes the path of least resistance, and that usually means the rear end of the block gets reduced flow. a four cylinder block usually wont be affected by the removal anywhere near as badly as a six or eight cylinder.

the size of the hole in the thermostat fine tunes the flows and therefore the pressure of the flow (not the preasure of the sealed system), which ensures the coolant reaches the back of the block in the correct amounts.

by all means take the temperature controller out but do not remove the restrictor, that hole in the center is that size for a reason.

[rick130]

thanks Inc, you said it far more elegantly than I did.

[Bigbjorn]

fluid dynamics... he doesnt mean it in terms of gallons per hour he means it in terms of the coolant flowing thru all parts of the block. with out the restriction of the thermostat aperture the coolant takes the path of least resistance, and that usually means the rear end of the block gets reduced flow. a four cylinder block usually wont be affected by the removal anywhere near as badly as a six or eight cylinder.

the size of the hole in the thermostat fine tunes the flows and therefore the pressure of the flow (not the preasure of the sealed system), which ensures the coolant reaches the back of the block in the correct amounts.

by all means take the temperature controller out but do not remove the restrictor, that hole in the center is that size for a reason.

There was a series of excellent technical articles on cooling and cooling systems in the U.S. magazine "Skinned Knuckles". I will look for them and get my computer literate son to scan them onto this thread. Offenhauser racing engines always had a four branch water manifold (looks like an extractor exhaust system) taking the hot water out of the top of the engine above each cylinder. We used to drill and tap the cylinder heads of side-plate Holdens used in speedway midgets above each exhaust port and fabricate a six branch manifold to take the water out and back to the top tank. Chrysler side valve engines used to have a water distribution tube in the block behind the water pump to evenly distribute the coolant all the way to the rearmost cylinders.