forum.audiv8.com Foren English Audi V8 Forum thermostat

hi,
can anyone tell me how to replace thermostat on ABH.plz step by step. i have ElsaWin 3.3 and ETKA 7. i have the only V8 in saudi arabia.no mechanic and parts are difficult to get from audi S-AUDI arabia.is there anyway to check the water pump without removing it?thanks a lot

Hello there, if you will change the thermostat look between both timing belt covers below control valve, but bevor you try to change the thermostat you should drain your cooling liquid from the radiator and the engine.!! But look to the position of installation !!! If you will change the water pump remove the left cover from the timing belt and than you can look inside the housing. So now you need a flashlight, or maybe not?? And try to turn the pully on the right below the big cog from the camshaft (grey iron pully without any gearing). normally you can turn the pully.! But take care and don´t change the positin from the timing belt.!!!

Thanks Florin!i will change thermostat only but i am not sure about steps.plz correct me if i am wrong:
1.draining of coolant
2.removal of return hose pipe from radiator and engine
3.Open supporting clip for bottom coolant hose and take off top part.
4.Unscrew hose at thermostat housing.
5.Removal of thermostat housing by removing two bolts.
6.replacing thermostat and re installation in reverse order.

here i have two questions:
1.can i use AcDelco coolant rather than G11?
2.what is the type of bolts at thermostat housing, will i need any special tool to remove these?

Hi Munir,
look here for some (fuzzy) pictures: http://www.audiv8.com/german/faq/faq_show.php?id=150

I try to translate the instructions picture-wise. All advises (RH and LH) in driving direction!

1st. pic:
Drain the coolant at the lower side of the radiator meanwhile the coolant reservoir cap is opened.
Withdraw the upper coolant hose on the RH cylinder-block between the timing belt covers, as shown in the picture.

Then withdraw the lower hose. The thermostat is fitted behind it´s cap.

2nd pic:
Screw out the two cap bolts. Therefor a TX 30 Torx wrench is required. Manipulate the old thermostat out of it´s housing.
Clean all seal faces.

3rd pic:
Fit in the new thermostat. The small vent valve (as shown in pic 3) must be bound upward.
Reinstall the thermostat-cap by using a new seal. Tighten the bolts with 10Nm.

Forget about pic 4 and reinstall the two coolant hoses.

Filling and bleeding (not shown in any picture):
Switch ignition on. Engage the AC to HI-level. Turn ignition off.

Fill up the coolant (total 8,5 liters) 50 :50 with G11 or another coolant in the same color (green, blue or red) your system was filled with.
During filling procedure, compress the upper coolant hose a multiple times to support deaeration of the cooling system.
Close the cap of the coolant reservoir as it is full.
Start the engine (AC still HI) and keep it idling with increased revolution level (2000-3000 rpm). You may exceed 4000-5000 rpm for short moments, even to support bleeding.

After engine has reached about 100°C stop engine, wait for 5 to 10 minutes and open coolant reservoir cap CAREFULLY (pressure).

Top up coolant to max and close cap. Start engine for another while and add coolant if necessary.

That´s it.

Hello Munir,

With respect to the two bolts/screws that hold the thermostat housing, you must be careful loosening them. At least two members made the experience recently, that (part of) the thread came out as well! Maybe this was due to too much tightening during an earlier thermostat change, but anyway, be careful.

Good luck, Eric

Thanks Tim for your illustrative guidance. i ll try on coming weekend.and post the outcome

Thank you Nap, i think i ll be careful.

Hi Tim, what may happen if i remove the thermostat without fitting a new one coz the area i live the temperature never comes down below 10 C and most of the day time even in January it stays above 20? so i use heater occasionally. Summer time when A/C z working all time there is always fear of overheating with oldies like mine .1992 4.2Q.

Hi Munir,
you must not drive without any thermostat has been fitted!
The engine will never reach it´s normal running temperature, even if it becomes not too cold in Saudi Arabia. Also in your county, driving without thermostat entails, that the engine, the coolant and the engine oil never get hot enough. The fuel consumption will increase significant (okay may be, this is the smallest problem in your region ;) ), because the mass of the injected fuel depends not only on the acceleration but on the coolant temperature. The ECU will always raise the fuel flow, as the engine temperature is low. And the worst is: Due to the increased mass of fuel injection, the wear inside the cylinders will increase rapidly. If you have really bad luck, piston(s) will be destroyed, because the excessive fuel will flush away the lubricant from the cylinder walls.
So you better try to get a new thermostat. May be, you order overseas?

Best regards

I have sent you a private message. Click the flashing button in the header of this site.

Best regards
Tim

it was a surprise for me when i went to remove the thermostat (pic 1).it was already not there.before removing its housing i checked with a mirror (pic 2).the car is with me for 5 years.i left it with Audi service center in Jeddah for two times. once for replacement of burnt distributor(i still have) after probably over speeding 252km/h.may be at that time they mechanic may have removed it to keep the car cooled down.i imported it from japan Yanase company in 2005.it boils water after 5km and i keep the cap loose so that steam may escape. can it be due to improper ratio of coolant:water?i think there is more water than coolant

astonishing! Even in hot areas a thermostat should be fitted, to regulate the coolant temperature. Driving without thermostat may only be a compromise as the thermostat does not open (completely) so, that the engine overheats.

I don´t believe, that the (quick) boiling depends on the ratio of coolant fluid and water.
It rather might be a result of inadequate bleeding.
Another very bad reason for the coolant boiling could be a burnt cylinder head gasket.

thinking of worse! in case if head gasket is damaged there must be some mixing of oil visible in coolant in the form of floating oil bubbles.i have observed that mechanics in temperate areas tend to remove thermostat.there is no question of opening or closing of one coz it is not there as an obstruction to flow of water from engine to radiator.

oil bubbles will appear in the coolant as the gasket is burnt. Of course this can take a little time.

In your case, if believe in imperfectly bleeding.

It´s useless to remove a thermostat in hot areas, even if some mechanics do it. As the thermostat is working perfect, it will open due to it´s normal regulating temperatures. As the thermostat is full open, for the cooling system it is like that, that there is no thermostat fitted.
But the working temperature of the engine will be reached much later (or never), as no thermostat is fitted.

well how much time for bubbles to appear?i ve this problem for over 6 months.never went beyond 5km. luckily my work place and all utilities r within this area. if i need to go far i use a cab or call a friend. i totally agree with your opinion of fully opened thermostat is like there is none when engine is hot.there r water drops from exhaust in morning briefly after starting i think which is normal. i was just telling what people do.by the way is there any special way of bleeding the cooling system other than pinching of upper hose 2-3 time after fill up.presence of air in liquid is one of the commonest cause of poor flow.

it´s sad, having a car that´s only usable for short trips in the neighborhood.

Water drops in the exhaust gas (specially with cold engine) are normal.

Try bleeding with opened reservoir. Top up level and let the engine run with opened filler cap until it has reached it´s normal temperature (about 95°C). The heater of the passenger compartment should be turned to max heating position, but the blower must be turned off!
After bleeding there must not appear any more bubbles. But the coolant level may increase during acceleration and even slump during deceleration.

Dear Munir,

welcome, you are first member from Saudi-Arabia! Please feel free to post a picture or two of your car, we'd are very curious about it

Thanks

Bastian

Salaleikum

Thank you! i work in saudi arabia. actually i m from pakistan and a big fan of audi/vw.
i ve posted one picture.it was taken with cell phone camera so not very good resolution.i ll post more.i believe this is the only V8 in this country as told by Audi saudi arabia. they keep a record of all audis here. they take it from license and registration authority.

Great!

I've heard of V8 running in Dubai recently, but haven't seen any when I was there last time.

Do you have any specific problems with sand, dust, salt or heat besides the described ones?

Is your V8 running in Saudi Arabia since the beginning or is it an imported car? Can you tell a bit about the interior (or provide another picture)?

Thank you very much!!

Bastian

Hi Munir,
are you really located close to Yemen? Interesting in which corners of the world a V8 can be spottet.
I worked around Dammam (Ras Tannura) 20 years ago and later in Rawalpindi and Peshawar. Just at the time when the V8 was born. Saudi was a bit boring, just a big sandbox, but in Pakistan I had a nice time.
Keep in touch and take care about the V8

yes i am near saudi-yemen border.do u know the people in pakistan who own V8.actually i am pakistani so next vacation i ll go there in Rawalpindi possibly in Jun/July (to watch FIFA world cup on TV in vacation).i ll be glad to see V8 in Pakistan.it was not easy to maintain Audi in pakistan at that time.In Saudi arabia the company came in mid 90's but in pakistan they landed in 2007.Here in SA people keep expensive cars just to show (i may be wrong)but in Pakistan i have met some people who have real love with cars and they keep this love for years e.g. i have not seen a single VW beetle (older one) in SA but u ll find 100's in Rawalpindi only.

Hi Bastien,
My car came in saudi arabia in oct 2005. one of my friend imported it from Japan.sand, dust and heat are really big problems here.on ecan easily ruin his ride if not aware of these things. driving on high speed through a sand storm very badly damages the front of cars especially paint, headlight glass and plastic work on bumper etc.if you r loosing little coolant in desert heat the engine may quickly heat up. once i was going to Riyadh and i faced a sand storm.despite of the fact i slowed to below 40kph, there was damage to paint work on front bumper.i ll soon post pictures of interior which is satisfactorily nice.
thanks for your intrest.

walaikum Salam

Hello all.
rather than continue my enquiries in the general section, i thought it might be appropriate to continue here in related threads.

recap.
My car has taken to over heating. After initially running with a fairly low temp for a while, it then went to high temp. The initial sign of something wrong was a low coolant level- dashboard diagnostic warning, confirmed visually at the expansion tank. It drops well below bottom level of the tank, but fluid happily returns to the tank when pressure is released.

A compression check shows all cylinders being relatively healthy. No remarkably low readings.

I need to check the thermostat. Unfortunately, the 2 screws are very tight. The torx tool I was using deformed. So I need a more direct route to those screws, and the radiator must come out.
I've not had a type44 apart before, so some pointers would be appreciated.
I want the rad out, clear access to the 2 bolts for the thermostat, and any possible repairs if the screws do pull material out with them.
It's a shame really- the hoses were replaced (prior to my owning it) at the same time as the cambelt. But the thermostat was kept. Doh!

any helpful documents/photos showing what needs to come apart would be great.

HI,

you still didn't tell how high the temprature went - probably the problem is a pressure problem due to a broken/sticky valve on top of the expansion tank. That's also not so quite unusual...

I have parts of an English repair manual/self study program I can send to you as an intermediate help (email address required). I'll ask at the US mailing list, probably somebody has the complete manual.

Bastian

I knew i forgot something.

I don't recall the actual temp that it got to, but it was about 2/3 full scale, started rising rapidly, while at a constant road speed of 70ish.

It's done it at low speed, high speed, 50ish. But it also went several trips without a problem. I'm fairly confident the thermostat will be involved, what with the cool running temp during the cold winter months.

Hi,

the thermostat gets stuck at a certain position, usually. Commonly, it gets stuck in open position, leading to an engine staying too cold during winter months or requiring too much time to become warm.

I've never heard of a thermostat suddenly closing during driving and staying there... but I've had the same symptom as you describe it once in winter, when I had too less G12+ in the cooling circuit, resulting in a frozen radiator. This in turn resulted in >110°C and, consequently, in a blow off of the overload pressure.

All this still sounds more like a clogged radiator to me, but give the thermostat a try.

Bastian

Once I have the rad off, the thermostat is coming out. It's peanuts cost wise, but a major pain if it needs doing later. Especially considering that the bolts are so well seized, that it is likely some serious effort is required to get them out.

I much prefer to do these things properly, once, when time and funds permit.

I just need to get the front to pieces.

Hi,

remove the front bumper (some tricky screws, somewhat more complicated than on a usual Typ 44, unfortunately), remove the head lamps, the lock carrier (guess it's called so) and finally you can move the AC radiator downwards and remove the coolant radiator.

There may be easier ways to accomplish a removement of the whole front, but I'm not aware of one. Just take care that the AC circuit remains closed!

You said the campbelt has already been changed - do you mean the engine timing belt or just the flat belt for the auxillery aggregates? If the engine timing belt is still the first one, you should change it asap, as Tim also proposed.

Regards

Bastian

I'll have to dig through all the papers, wherever they are, but to my knowledge, the critical timing components and belt were replaced about 6-8months prior to me owning it. Which means a lot less than 10k miles ago.

sounds like this is going to be a less than pleasant job on it's way.
hey ho

Hi,

you can remove the radiator, as far as I know, also without removing the whole front! Wait some hours until you get a second meaning from somebody else here

Good to know that the timing belt has been replaced, one problem less

Regards

Bastian

Yes you can remove the radiator without dismantling the whole front.
May be it's sufficient to remove the aux electrical fan only, so that there is space enough to thump the thermostat cover bolts.
Before you can dismantle the radiator, you have to remove the auxiliary and the viscous fan (mind left-hand thread of the central nut).
As I have renewed my whole timing stuff, I've even removed the radiator only .

So, some progress, of sorts

I couldn't get the radiator out, but did release it sufficiently to get access to everything.
The thermostat housing screws came out, fortunately.

The thermostat was quite badly covered in crud. And very tight in the housing. I'm fairly sure it was also in upside down (bleed/vent at the bottom). I've tested it by cooking it in a pan of water heated on the stove, and it opens and closes ok.
I've flushed through the block in both directions, and while there is very little debris in the water coming through.

I've also flushed through the rad while it's on the car, and there is no obvious debris coming through. But I'd like to take it out for a better look.

The oil cooler under the rad is free and out of the way.
The rad has 3 rubber hoses on the right (viewed from driving position) which are off.
The aircon rad is loose, but still connected.

Presumably, I need to remove the whole cast(?) bracketry radiator mounting to get the rad out?

Hi,
to dismantle the rad completely you have to remove the bumper.
As I remember now, I didn't remove the rad when I was renewing the tooth belt.
At the bottom of the rad you find to further rubber bearings, fixing the rad.
Be prepared, that these bearings will be cracked.
You should also prepare new seals for the gearbox-oil-rad.

The thermostat was not seriously fitted, when the valve was bound downwards.

But the question is: Is there any need, to dismantle the coolant radiator? You can flush the system with special fluids as long as there is no thermostat fitted.
By the way: Tap the threads of the cover cap and insert new bolts with a smooth coat of ceramic or copper grease.

After an interesting day of ups and downs, i have the following situation.

1. I ran the engine without the thermostat. Got it warmed up. But no temperature indication at all- maybe anomalous readings previously? Where are the temp sensors?

2. While running, expansion tank cap off, there is a regular stream of bubbles into the expansion tank. Cap on, the system becomes pressurised very quickly, and the hoses become hard and noticeably balooned. Even though I've made big efforts to ensure no air is trapped in the system.
Head gasket failure?

3. Very moist exhaust- but this may be due to 2 months of sitting unused.

4. Whoever did the timing belt needs shooting. Three of the cover bolts on the right hand belt cover have no hexagon left. So the front of the car has to come apart to get a drill in there to drill the remains out.

5. both fans are running- the viscous fan seems to work ok. Should the electric fan be running constantly?

So, not really a success. And a small pain in the derriere if one or other head gaskets have gone.

Hi,

the symptoms sound a bit like a head gasket problem, but I wonder that you've noticed nothing strange on the comression test. Also, the head gaskets on the PT are usually very reliable.

Regarding the sensors. One is located in front of left head, directly where the cooling fluid hose is connected to the head. This is the "primary" sensor. Only if this sensor fails (shortened or open), the sensor at the radiator (bottom) is considered. This are at least the observations I've made, on both the pre- and post-face-lift instrument cluster. Both sensors are subject to malfunctions over the years, an exchange would make sense (shouldn't be too expensive).

The electric fan is running whenever the A/C is enabled, otherwise only if the temperature exceeds specific limits (I have 98, 103, 108 degrees centigrade in my mind for the respective fan speeds). You can test if the fan speeds work properly (requires an intact fuse and intact relais) by plugging out both coolant sensors. The system will then assume a temperatur of, I think, 110°C and goes to maximum fan speed. The engine must be running for that test. You'll be surprised how loud this can be!

Important about the viscois fan is that it becomes "strong" when the engine warms up. You should not be able to stop it literally by hand (I don't have to tell you that you shouldn't really use your hand to try that when the engine is running...). If the coupling appears to not work properly, it may still be the radiator who remains too cold. Did you try if the radiator becomes hot on top and at the bottom when the thermostat isn't built in? If the radiator is clogged, heat distribution is usually unequal.

Regards

Bastian

Well, another day ticks by, and pretty much certain there is a head gasket failure. The symptoms now are very marked, both in exhaust moisture, and pressure increase in the cooling system. You can actually watch the hoses balooning, and the fluid level being pushed down. I'm surprised the pressure relief in the cap doesn't kick in. It's probably kaput, too.
I did the compression check about 3 months ago, and I guess at the time, the problem hadn't become so great. I think a recheck of the compression is in order, to confirm. What values would you normally get on the PT engine?

I spend a lot of time out of the country, so getting on top of these things can be a bit of a challenge.

I am subscribed to 'the list' at audiworld (just under a different name). I've been watching the discussion, but will chip in shortly.

Time to get it all to pieces for the future head work!

Hi,

sorry to hear that the gasket seems to be broken. The good thing is that it's not voodoo to exchange both of the gaskets and you could use the chance to also exchange the valve stem seals and all the oil seals in the heads and the timing belt as well - then you are happy for the next 60k miles!

But more interesting should be WHY a gasket failed, as this is really unusual on the V8 3,6 engines. It would be really bad luck if you repair everything and some weeks later you've the same problem again.

If you need anything, like part lists, please let us know - we'll support you wherever possible!

Best regards

Bastian

Wich colour has the cap? Black or blue?

Some partdealers have carbondoixide detecting stipes,
with these you can make almost 100% sure that the headgasked is failed.
Hold the stripes in the coolantreservoir while the engine is running and wait for colourchange.