Air in the coolant
Discussion
Another question for you experienced Wedge owners. The basic problem I am having with my 350 is trailing throttle hesitation, which a garage has tried to fix by fiddling with the flap - see other thread. I think it is associated with the coolant temperature gauge seeing the wrong temperature, as there is air in the system. The same garage has replumbed my cooling system saying that TVR did it all wrong. However, this has had no effect and I am still getting air in the system. I replaced the radiator a couple of months ago, as this definitely had a leak, along with new caps. However, each time I drive her and leave it to cool down more air appears. It collects in the head area and when the swan neck is removed there is no coolant to be seen. On the other hand if I look in the catch tank it is full. When I release both caps the swan neck fills from the catch tank. There is no sign of any external leak. Any suggestions where the air can be coming from??
GA that Garage of yours sounds really worrying. The cooling system with the rad being so low is difficult but to say that TVR did it all wrong is incredible. Just what have they changed? Do you have a flat cap on the swan neck? ie not a pressure related one. If you top up the flat cap at the beginning of each day then it should be self bleeding bar what your garage has done.
I couldn't agree more. The garage is more than worrying; I think they are incompetant 
. A view I know is shared by at least one other PH.er. Unfortunately they advertise as being TVR specialists. Obviously I can't say more in the forum, but I'll be pleased to give you chapter and verse if you mail me.
As far as the plumbing is concerned, yes there is a new flat cap on the swans neck and a pressure cap on the top up bottle. I've kept topping up the swans neck, but the air keeps appearing. The only signs of coolant loss ar when both the swans neck and the top up bottle are full, and then the excess expands out of the bleed into the overflow, when hot
.
. A view I know is shared by at least one other PH.er. Unfortunately they advertise as being TVR specialists. Obviously I can't say more in the forum, but I'll be pleased to give you chapter and verse if you mail me. As far as the plumbing is concerned, yes there is a new flat cap on the swans neck and a pressure cap on the top up bottle. I've kept topping up the swans neck, but the air keeps appearing. The only signs of coolant loss ar when both the swans neck and the top up bottle are full, and then the excess expands out of the bleed into the overflow, when hot
.Hey Chaps!
Very interesting. I was worrying about a loss of coolant just the other day, and was about to send the car in to my engineer for him to have a look. I know the gaskets were replaced not long ago so I should assume it is not this. Is this a common problem with Wedges?
What is the 'flap' people are talking about? Fuel system? You can tell I'm new to Wedges!
firefox
Very interesting. I was worrying about a loss of coolant just the other day, and was about to send the car in to my engineer for him to have a look. I know the gaskets were replaced not long ago so I should assume it is not this. Is this a common problem with Wedges?
What is the 'flap' people are talking about? Fuel system? You can tell I'm new to Wedges!
firefox
It's not unusual to have to top up the water; its the only thing in caps in the owners manual.
What nneds to be established is the amount. I had a head gasket failure on my first 350 and it got through about half a gallon an hour. An air leak on a hose or the rad is most likely.
The flap is a cat flap type device that the air flows past and measures the amount of air flowing into the engine. It was thought of as second best when the hot wire came out until the tuning boys learnt of the drawbacks of above 6k revs on the newer system; not that you rev that high do you? The flap cars have no rev limiter and will rev round to about 7750 but sometimes only once.
Head gasket, I wouldn't assume that this is ok just because it has been replaced. Has the cause of the failure been addressed?
What nneds to be established is the amount. I had a head gasket failure on my first 350 and it got through about half a gallon an hour. An air leak on a hose or the rad is most likely.
The flap is a cat flap type device that the air flows past and measures the amount of air flowing into the engine. It was thought of as second best when the hot wire came out until the tuning boys learnt of the drawbacks of above 6k revs on the newer system; not that you rev that high do you? The flap cars have no rev limiter and will rev round to about 7750 but sometimes only once.
Head gasket, I wouldn't assume that this is ok just because it has been replaced. Has the cause of the failure been addressed?
19560 -
Thanks for that.
The car will be going in to be fettled and have one or two little niggles fixed. He's already inspected it and thinks it's rather good and a straight car. I'll ask him to check up on the cooling system and look for possible head gasket failure as well as check the sticking throttle which I experience occassionally. I tend to do double-declutch on downchanges and though I only blip the throttle gently I have had the engine rev wildly for nor reason - also a little after starting when the engine ticks over fast too.
cheers
firefox
Thanks for that.
The car will be going in to be fettled and have one or two little niggles fixed. He's already inspected it and thinks it's rather good and a straight car. I'll ask him to check up on the cooling system and look for possible head gasket failure as well as check the sticking throttle which I experience occassionally. I tend to do double-declutch on downchanges and though I only blip the throttle gently I have had the engine rev wildly for nor reason - also a little after starting when the engine ticks over fast too.
cheers
firefox
P.S.
I think I've only revved to about 5000 so far - if that. It is possible to get plenty out of an engine without too many revs - so you can have a lot of fun without the noise! I should imagine there is some power drop off after 5000 or 5500 with this sort of engine in any case - or does someone have a power curve that shows otherwise. 7000 plus revs and I should imagine certain engine parts hitting each other!
firefox
I think I've only revved to about 5000 so far - if that. It is possible to get plenty out of an engine without too many revs - so you can have a lot of fun without the noise! I should imagine there is some power drop off after 5000 or 5500 with this sort of engine in any case - or does someone have a power curve that shows otherwise. 7000 plus revs and I should imagine certain engine parts hitting each other!
firefox
Cheers FF - the sticking throttle could be the butterfly valve at the enrtance to the plenum chamber. They can get gunged up and need to be cleaned; in some cars this can make a surprisingly big difference.
For the revs I was merely trying to point out the differences between the two systems which are exploited by the engine tuners.
The 350 develops maximum torque at 4000 and max power at 5280. There is only dire emergency as an excuse to go above 6000 really. I hardly ever rev above 5000 and never above 5750. There is plenty of torque above 2000. The other engines vary though. For legal reasons are you able to say which engine etc that you have yet?
>> Edited by 19560 on Thursday 6th November 13:54
For the revs I was merely trying to point out the differences between the two systems which are exploited by the engine tuners.
The 350 develops maximum torque at 4000 and max power at 5280. There is only dire emergency as an excuse to go above 6000 really. I hardly ever rev above 5000 and never above 5750. There is plenty of torque above 2000. The other engines vary though. For legal reasons are you able to say which engine etc that you have yet?
>> Edited by 19560 on Thursday 6th November 13:54
It is ok for me to mention that the file contains a letter from the factory dated July 1990 stating that the " ...engine is 4230 cc (4228 is the normal figure quoted for a 420, but i have also seen 4226 stated - but does it matter?) and not 3498 cc as stated at the time of typing the V55/3" from Jackie van den Berg, Sales Administrator, TVR Engineering.
This is the letter that has been referred to several times on the thread regarding this car and its sale at Barons.
How it all fits in to the varying and sometimes conflicting information I have received so far - I don't know. There appears to be a choice for me and others to make - do we take what is documented as being true, or what some people say (and even heresay) and which may not have written back up?
To be or not to be - is that the question?
Written or rumour?
firefox
This is the letter that has been referred to several times on the thread regarding this car and its sale at Barons.
How it all fits in to the varying and sometimes conflicting information I have received so far - I don't know. There appears to be a choice for me and others to make - do we take what is documented as being true, or what some people say (and even heresay) and which may not have written back up?
To be or not to be - is that the question?
Written or rumour?
firefox
3498 is a nonsense anyway, the stock is 3528. Have you checked the the engine number on the block tallys? The larger cc engines develop peak power and torque further up the rev range but I still wouldn't rev them any higher. Most fun way to find out about your engine - does it blow away 350s easily?
19560 said:
3498 is a nonsense anyway, the stock is 3528. Have you checked the the engine number on the block tallys? The larger cc engines develop peak power and torque further up the rev range but I still wouldn't rev them any higher. Most fun way to find out about your engine - does it blow away 350s easily?
My 1984 350i V55 also states 3498cc
originally! Doesn't make it right though. Mechanically the early 350 engines are Rover SD1 Vitesse, at 3528.
bobble350 said:
Are you sure it's air and not combustion products, if it keeps appearing and is getting worse it's probably a head gasket failure.
I don't think its a head gasket as I've been having this problem for about six months and it doesn't appear to be getting worse. Also I assume that if the gasket is leaking the coolant system will over pressurise and blow coolant into the engine bay, and there's no sign of that. As I say - very curious!
dickymint said:
My head gasket leak manifested itself as white frothy(like a shaken bottle of lager) bubbles in swan neck and header tank. Gasket renewed with cam change and sorted.
I looked for this a few months ago when the problem first appeared, and there was no sign. I also tested for a leak with a chemical test kit I borrowed from my local garage, and it didn't show any exhaust in the coolant.
I assume the air is getting in when it cools down. The normal operation is that when the engine temperature drops, coolant to refill the system comes from the header tank (grandmother and eggs!). This does not appear to be happening with mine, and the header tank stays full while the swans neck is empty.
Gassing Station | Wedges | Top of Page | What's New | My Stuff