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Rough Running


jamesdennison
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On my way back from Silverstone on Sunday my car seemed to go out of tune. Loss of power and consistent rough running with a misfire that kind of isn't fully missing, but not right. No horrific metallic noises or anything so I limped home.

 

I've got good sparks, timing is spot on and carbs balanced but car not happy with lots of vibration at idle.

 

I've got a compression tester on order and I'm expecting issues with no.4 cylinder as there was a puff of smoke \ vapour when I took out the plug. Also getting similar puffs if I remove the oil cap with the engine running.

 

Ideas folks!

 

I'm pretty handy with a spanner, but not attempted engine work before.

 

Car is GT6 convertible with triumph 2000 ME engine

 

 

James

Staffs

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This could be anything from a duf rotor debris in the fuel supply to one of the carbs, or heading for head gasket

puffs of vapour/smokey form plug holes or oil filler is not abnormal

There is always fumes from the filler if removed

if the puffs from the filler were rythmical with a particular firing then a head gasket is possible

 

do the cheap and basic checks and some test before you do any major guess work

compression test is good start, do this with all s plugs out and a open throttle

 

pete

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ME or most mkII engines dont suffer HG problems but if you do , have a look at the nut and washers

if they have deformed it looses clamp load due to a drop off in torque,, more common on mk1

but soft washers seem a problem even on TR4 its evident

just bear this in mind should a refit be needed

 

pete

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I had this happen to me once albeit on a viva hc but after weeks of trying everything it turned out to be one of the plug leads failing. Worth checking this before spending lots of money replacing parts. Symptoms you describe were very similar.

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I'm not going to do anything expensive until I've checked compression. But I have some spare leads so that is a good call!

 

I have a spark tester thing I bought years ago which fits between the lead and plug - all looks to be working ok.

 

Mixture also seems good as tested with colour tune, carbs balanced, timing checked and carbs were refurbed by Adrian turner a few thousand miles ago so I'm expecting head problems.

 

Probably Monday before compression tester arrives.

 

If it is the 'head I reckon I'll have a go myself, probably with a refurb via club shop or fitchetts if they do them (10 mins down the road). Looks straight forward job if I can get it off!

 

I'll update when I have some readings.

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they can get corriosion on the studs making a easy lift off a fight

    Ive been known to jack a head and car off the ground and it stillhung on

 

         a good stud box is usefull to remove the studs first, 

           on one particular stuck head I managed a gap and  cut the last offending stud off with a hacksaw blade through the small gap  then punched the stud out the head , the stud end unscrewed with fingers..    

               her's hoping  that like most do it will with a gentle nudge break its grip and up she comes 

 

                   if the heads studs have lost torque they generally fail between  the narrow section of two cylinders 

                         Pete

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  • 2 weeks later...
  • 2 weeks later...

Finally got a working compression tester.  Not good news though

 

Cylinder     Dry      Wet

1                168      173

2                168      170

3                169      179

4                62         60

5                152       153

6                165       180

 

New territory for me this, but planning to take the head off and send for conversion to unleaded - is this the right thing to do or could there be further troubles?

 

I've pretty much tackled everything else on the car but never needed to get inside the engine so my knowledge and "engine" tools are limited.  I'd like to have a go myself so I understand how it works ... but a bit nerve racking.

 

What do you reckon folks?

 

(and I'm off on holiday for a couple of weeks tomorrow so I may not reply quickly .... but at least I can cover the studs in plusgas for a fortnight)

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Thought I'd have a quick go on the studs to get it out of my mind while on holiday.

 

Four of the easy to get at ones came out no problem - so fingers crossed the others will come out too.

 

Had to stop now as the hardest part of the job so far has been removing the removed stud from the stud extractor.  Just broken my cheapo aldi vice and got a whiff of impending accident involving my knuckles so I need to invest in a better vice.  :)

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60 is looking valve seat problem, but have a careful look at the gasket it may have blown out to an oil way .

 

you dont need any special tools   screwdivers , pliers, 

7/16  1/2   9/16 spanners and sockets , a good ratchet and a extension bar to get  the under the manifold bolts.

 

 best to remove water pump assy. makes all a bit lighter.

 

with head off tip upside down and pour something thin, in the chambers if a valve has burnt the liquid will run into the manifold bores;

 

easy to get valves out quick,to have a look at  the seats>>>>>

 

block the valve head with a block of timber or a socket sit the head and a valve over the socket,  place a socket over the valve stem cap big enough to clear the collets

 

give this a good whack and the collets will jump out and the springs detach , all 12 will be out in 2 minutes

 

putting them back needs a spring compressor, 

 

if the seats need a paste grind you wont affect the lead memory, these heads will last years without inserts or addatives

 

if the seats need re cutting thats more invasive and inserts on the exhausts may prove the right move

 

its not normal to fit inserts to inlets unless the seat has degenerated and the valve is recessed. below the chamber face.

 

dont jump  till youve looked and found just whats failed 

 

Pete

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  • 4 weeks later...

Well, all going well so far.  Rather than tackling everything at once I've spent an hour or so every few days and taken time and care.

 

Head studs came out without any bother at all.  Water pump assembly, rocker shaft and inlet manifold have been off before so also came off easily enough.  Everything looked clear so I got out my rubber mallet ready for a battle...... but just a little hand pressure and away she came !

 

What do you mean by something thin Pete?  I've got some modern engine oil (5/30 I think) will that do?

No sign of any gasket failure - see pics.  I didn't lose any oil / water and no overheating so I didn't think that was the issue.

 

The chambers (is that the right word?) are very rough and corroded and the bottom of the valves don't look too good either so I am very tempted to send the whole head off for peace of mind rather than work on them myself.  I also attach a pic of the top of the pistons - do these look ok?  Are there any tests I should be doing to check them ... or even a give them a clean? 

 

... and even though the studs came our without problems, should I change them as a matter of course?

 

.... and can anyone recommend someone to recondition the 'head? (Chris Wittor maybe if he does that work)... I'm near the black country so plenty of engine specialist round here, but good to get a recommendation.

 

Cheers for the help so far.

 

James

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ask Garth Club shop std head £370 ,   excellent supplier is used ,been there for a tour , first class. 

 

 

any machine shop should do the work ok , by thin some use paraffin/.petrol  , but any oil will do ,  if the seat is shot it will like a dripping tap ,and  work through quite quickly to the port side.

 

just scrape without digging the top faces of the block and pistons they will clean up fine, 

 

in general you only need unlead inserts on the exhausts.

 

may be think about new guides

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Yep, 'something thin' is petrol/white spirit/etc.  Basically anything that can leak through small cracks and gaps and won't leave a residue you have to then clean up.  Use some old spark plugs as they're never quite the same after they get wet.

 

In theory the liquid will just sit there until you get bored and turn the head over to pour it out.  Given your wet and dry compressions results I'd expect that to happen on most cylinders but it to come pissing out past the valves on #4 - so don't stand with your feet under the head and the ports pointing at your crotch when you do this test :)

 

 

Here's Ed China doing the same test on a Spitfire (from @17:45)

https://www.youtube.com/watch?v=djKErMfk1BM

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I lost all respect for Ed China when I saw him use petrol for this test on Wheeler Dealers - stupidly dangerous, and no warnings given, and petrol poured all over his tool box.  With all the studio lighting and camera equipment in the workshop I was stunned there wasn't a fire.

 

Any low viscosity liquid will do, and the less volatile the better - white spirit or paraffin would be considerably safer, and still I would do it outside with plenty of ventilation and a tray to catch any spillage or leakage.

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Need a plan b folks.

 

Just done this test (carefully, with petrol, outside) and there is no loss at all to any chamber after a good 30 minutes.

 

Does this mean the valves / head is ok?  if so what else could be causing loss of compression?

 

I did the compression test three times (2 x dry 1 x wet) on cylinder 4 and got the same low readings every time so I am confident that my readings are correct.

 

Could this be piston ring failure? .... I read that the wet test is used to diagnose this and should give a higher reading if this is the problem.  It is always possible I didn't squirt enough oil down before doing the test.

 

As the weather has turned it looks like this has turned into my winter project.

 

Ideas and advice please folks! ..... and it looks like I'll owe a few pints at a future TSSC event!

 

Thanks

 

James

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What is the bore like? Did the gasket show any damage around that one?

What's the thread and outside like on the spark plug hole and the compression tester? I assume you removed it several times and it always give the same reading? I know mine is a very short thread so was wondering it this was a seating issue.

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The gasket is perfect .... One of my questions was whether it could be re-used (I guess not).

 

Yes, I screwed the compression tester in and out a few times to make sure I was getting the right reading as I was also worried that a poor seal would affect the reading.  The thread is fine. 

 

The inside of the cylinders (bore?) is clean and shiny without any sign of marking.

 

Just to recap....

 

Car was running fine (I drove 75 miles the previous day), then started running really rough with a misfire.  After checking everything obvious by the side of the road I drove 50 miles home with my eye on the temp gauge - but no sign of overheating.

 

When I got home I systematically tuned the car (as I have done many times).  First checking the tappets with a feeler gauge (all ok) then checking the timing with a strobe (12 deg btdc) then checking the mixture with a colourtune and balancing the carbs with a carb balancer.  I also cleaned all the plugs, ht leads, checked the rotor arm and inside of the dizzy and washed and oiled the K&N filters.  Electronic ignition so no points, and fuel was fresh.

 

By doing this I got the car to run marginally better, but the misfire still there.  I've had the car 15 years and I could tell it wasn't running right.  There was also a rhythmic puff of fumes coming out of the oil filler when off and also a release of fumes from plug 4 when I took that off.  Compression test revealed low pressure on no.4.

 

At the moment I'm down a few hours but not really spent any money.  I'm loathed to take it to a garage until I've done everything that is practical without needing specialist tools..

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no never reuse a head gasket unless your stuck in the middle of africa

 

if no4 is the oiled set of valves you could be into piston problems here

123 quite lean 456 richer, but 4 is seems  well oiled ??

 

roll the push rods on a flat table ..have you got a bent one ,  

pull the cam followers ..any signs of seizing ? 

 

are the rockers free , if one sticks on its shaft its possible it  will hold a valve open

 

keep rods and followers in their original places  best not to get them mixed about 

 

I would pop the troubled cyl valves out and look at the seats and check the valve guides  heights are all the same 

 

if gasket and seats are sound then  begin to think this   is  piston related   

 

Pete

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Looking closely at the pictures the area around number 4 appears burnt beyond the bore, a gasket leak, which would explain the loss of compression. If the valves don't leak I wouldn't bother replacing the head with an unleaded, there are a lot of threads on here and elsewhere discussing this.  It's generally believed the "memory" of lead is enough to keep your engine running OK indefinitely. I would clean the head up and put it back, making sure you have the right gasket (recessed bores or not, there's a stick out tab or not on the back of the gasket to indicate which it is).

 

Just a small aside, the three sets of valves at the front of the engine are much darker than the three at the back which would indicate your carbs aren't balanced/set up right.

 

Good luck!

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that blow from no4 would be backed by a lower result obtained on no5 

 

just looked on a better screen and Im with doug , before deep pocket sydrome strikes  clean and refit the orig head see what happens

 

you could pop the valves and examine the seats , give a reface with paste wont remove the memory,   full  machined  recutting  will .

 

Pete

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cam followers are all fine (lovely smooth motion) and the rods are good and straight.

 

So it sounds like the next course of action is the put it all back together on the basis that I did have a gasket leak? - I can live with doing that.

 

Carbs are balanced (I use carb balancer and then pipe and ear until I'm happy) but I've never been 100% happy with the mixture setting.  I used a colour tune and had to set both fully lean but the back one was always a bit more yellow so runs a bit richer.  It did run pretty well though, until this issue. 

 

Anyway, I'll get a (tabbed) gasket and get this lot back together again.  Am I ok to reuse the studs or should these be replaced as a matter of course?  A couple were rusty so I'd definitely swap those, but most look good.

 

Just watched a couple of youtube videos on grinding the valve seats - looks straight forward enough so seems daft not to do this while the head is off.  Am I right in thinking that I need to leave the face of the valves alone as this is the "lead memory"?  Am I ok to clean up the rest of the chamber.... and any advice on a cleaner? ..... I was advised to use oven cleaner when I cleaned the sump of my saab - is that a bad idea?

 

Cheers

 

James

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