rover p6 v8 auto 1974

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hornchurchmale
Posts: 23
Joined: Sat Aug 23, 2014 4:43 pm

Re: rover p6 v8 auto 1974

#11 Post by hornchurchmale » Mon Apr 06, 2015 10:54 pm

update. carbs rebuild using new seal. needles and jets not interfered with. idle and fuel flow set using hot engine and color tune on both banks.
runs lumpy when cold but when hot idles perfectly. power still seems low and after a stop..it really is slow ..then all of a sudden it will accelerate like a switch being thrown with decent performance ( as it ought to have). assuming I have a hot fuel ( gas bubbles) issue here. was going ok until I popped to local club meet where i thought it was suffering fuel starvation and managed 22mph.. when parking up it gave of lots of smoke and a bit of pong.seems front brake shad jammed ON.
releasing pressure by opening flu line to servo did trick and after calling off drove ( carefully) home. brakes worked ok all way home? an old guy at meet said he had had these cars before and said it was servo fault. smallest bit of crud it seems block a pinhole in it keeping pressure in system ( no idea why it only affects front) ps. recently renewed both front callipers and master cylinder. rears where stripped and reassembled as no issues found. handbrake v poor though did manage ( wow pigs do fly) to pass an mot .
hoping to do more than 130 miles this year...luckily to offset the drain on finances.. it is now tax exempt. will (after a holiday) do a compression test. send off for replacement servo and rob a bank to fund it all...hope you all had a nice easter.

kevin
Posts: 856
Joined: Sun May 12, 2013 7:49 am

Re: rover p6 v8 auto 1974

#12 Post by kevin » Tue Apr 07, 2015 7:31 am

What make is the servo?
I bought a brand new one last year from Powertrax and it was under £200.

Kev

suffolkpete
Posts: 1132
Joined: Sun Jan 23, 2011 11:54 am

Re: rover p6 v8 auto 1974

#13 Post by suffolkpete » Tue Apr 07, 2015 9:37 am

If it's only the front, then it can't be the servo, difficult to tell with these cars as the rear discs are inboard so you can't tell whether the rears are getting hot as well. If it is the servo, and it sounds as though it is if there is pressure in the system, then it is probably the air valve sticking, a common problem with these cars. You can buy a rebuild kit for the servo for around £60, or £150 for a recon unit.
1974 Rover 2200 SC
1982 Matra Murena 1.6

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Grumpy Northener
Posts: 1637
Joined: Sun Apr 03, 2011 8:26 am
Location: Hampshire UK

Re: rover p6 v8 auto 1974

#14 Post by Grumpy Northener » Wed Apr 08, 2015 1:26 am

Before doing anything else - disconnect the inline pressure switch that activates the brake lights - this is adjacent to the servo on the inner wing just a little further back towards the bulkhead - see if that cures the problem - there is a rouge batch of these switches in the market - when live / activated they generate heat - in doing so they create a small air bubble in the brake fluid - said air bubble then locks your brakes on :o - air bubble eventually disappears (with foot off the brake pedal) when the fluid cools and off come your brakes - if this is at fault then it's a simple fix by just replacing the switch you can even do it with system full of fluid (if you are quick enough to swop them over) - I found out the hard way - servo rebuilt, 4 x callipers rebuilt, 3 x flex hoses replaced, 2 number master cylinders later before a very wise old school trade contact said try disconnecting the inline brake pressure switch !
1937 Jowett 8 - Project - in less pieces than the Jupiter
1943 Jowett Stationary Engine
1952 Jowett Jupiter - In lots of peices http://Jowett.org/
1952 Jowett Javelin - Largely original
1973 Rover P6 V8 - Original / 22,000 miles

suffolkpete
Posts: 1132
Joined: Sun Jan 23, 2011 11:54 am

Re: rover p6 v8 auto 1974

#15 Post by suffolkpete » Wed Apr 08, 2015 9:17 am

I don't get that. Heat can't generate an air bubble in the fluid, what is more likely is that water in the fluid is being boiled, in which case a fluid change is due. But even so, any pressure in the system should be released as soon as the pedal is released if everything is working properly.
1974 Rover 2200 SC
1982 Matra Murena 1.6

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Grumpy Northener
Posts: 1637
Joined: Sun Apr 03, 2011 8:26 am
Location: Hampshire UK

Re: rover p6 v8 auto 1974

#16 Post by Grumpy Northener » Wed Apr 08, 2015 2:15 pm

I don't get that. Heat can't generate an air bubble in the fluid, what is more likely is that water in the fluid is being boiled, in which case a fluid change is due. But even so, any pressure in the system should be released as soon as the pedal is released if everything is working properly.
Most fluids that are heated to a high enough temperature will boil : (I don't have a PHD in chemistry or physics so please don't take me to task on this)

Wikipedia's definition of boiling is as follows:

Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding environmental pressure.

Surely if you have a vapour - then the this will create the bubble - ok we could go on to argue that it a vapour bubble not an air bubble has I originally described it :ugeek:

No water in my Rover P6 brake system either - it's been Dot 5 silicone for the last ten years - the inline switch can be the issue - not just with P6 Rovers either - any vehicle with this type of inline brake pressure switch can suffer - PC Market editor Russ Smith's Alfa Spider had the same problem several months ago - a simple change of the inline switch sorted it (sorted mine too)
1937 Jowett 8 - Project - in less pieces than the Jupiter
1943 Jowett Stationary Engine
1952 Jowett Jupiter - In lots of peices http://Jowett.org/
1952 Jowett Javelin - Largely original
1973 Rover P6 V8 - Original / 22,000 miles

hornchurchmale
Posts: 23
Joined: Sat Aug 23, 2014 4:43 pm

Re: rover p6 v8 auto 1974

#17 Post by hornchurchmale » Thu Apr 09, 2015 4:46 pm

many thanks helpful tips and advise. car has to wait to get attention here as off on hols soon , and car needs new servo and brake lines plus boss hates spending pension funds on 'IT' ..so avoiding working or spending on it keeps the peace. oil is clear and has been changed with new filter. am aware its high when cold and has started to drop when warming up but according to gauge is around 20-25 at idle with engine running a tad on cold side. new coil not fitted as assured the electronic kit works well with existing coil and a sports or high energy one not needed.
carb rebuilt using kits and float level checked using manual. lumpy running and slightly noisy? tappets when cold would suggest possible timing issue as fairly sure the colour tune at idle and hot on both banks is ok. strobe shows timing a 6 degrees btdc, springs in dizzy seem ok and everything mechanically good apart from the replacement vacuum unit. suspect it would be OK with very high vacuum but my engine only produces 18-20 "hg .at idle which isn't enough to activate it. it isn't 'holed' as a new replacement and blowing into it shows no leaks. so rely on mechanical advance only. will do compression test at same time as replacing servo and brake lines..ought tot be good for a divorce argument lol
occurs to me the 'tapping' noisy is tappets not pumping up correctly until oil thins a bit ..which is also when engine settles to a smoother idle around 650 rpm. ( trying to set lower gives cutting out issues and either stumbles or hunts-even though color tune shows its good burning colour. :? aware dealer may have changed oil pressure relief valve spring to show 'decent' oil pressure. but this is pure speculation and hopefully wrong!
will show compression rating later and may do wet and dry. in case I didn't mention it. servo being replaced as locked on front callipers at local car meet. old guy (84) whom had had several rovers telling me it common issue when bit of crud blocks a pinhole in it. ( new calipers and master cylinder already fitted) happy motoring all. on a side note see our older cars (40 years plus) are not only tax exempt but congestion charge and pollution charge free in london. ( think london to brighton run had a lot to do with that decision)

kstrutt1
Posts: 516
Joined: Sat Oct 22, 2011 8:55 pm
Location: essex

Re: rover p6 v8 auto 1974

#18 Post by kstrutt1 » Thu Apr 09, 2015 4:59 pm

The tappets should pump up in a few seconds even after sitting 6 Months mine only tapped for a second or so, to be honest, low manifold vacuum, tapping, poor performance and lumpy idle at low speed all point to the cam for me.

harvey
Posts: 286
Joined: Wed Jan 05, 2011 4:47 pm

Re: rover p6 v8 auto 1974

#19 Post by harvey » Thu Apr 09, 2015 5:25 pm

hornchurchmale wrote:servo being replaced as locked on front callipers at local car meet. old guy (84) whom had had several rovers telling me it common issue when bit of crud blocks a pinhole in it. ( new calipers and master cylinder already fitted) happy motoring all.
As it has a single line system, with one pipe into the servo, and one pipe out to all the brakes, how does the "bit of crud" manage to only block the servo to lock on the front brakes only? How does it know? Either it isn't the servo, or if it is, it's locking on the rears as well, you just don't realise it.
Currently over 35 years worth of fixing 35 boxes.
Hoping to reach 65 years worth of fixing 65 boxes.

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