Head Gasket / Misfire

[trg65]

Hi All,

Hope some can advise on Bad misfire, 

recently bought 4 weeks ago 1970 cp i was aware  it had a misfire and worn throttle throttle spindles, thinking a easy  fix plugs etc, the car had been standing for a  awhile. checked cylinder pressure all about 185 lbs. I can't see the throttle bodys having this much effect on misfire on and over 1/4 throttle opening,

so turn my attention to injectors.

Lumenition already fitted, new plugs,  all leads newish, strong spark,timing 10 degrees, tappets 10 thou ,Fuel pressure 105 psi, sent away for exchange injectors, fitted thees to day same problem, gutted, injectors tubes all polsing, checked most things meattering unit last on the list to change,

 noticed froth in radiator water,after seeing this may be the culprit, i've  decided to start  removing manifolds then head ,

ive read there is recessed and none recessed  not sure what this refers to any help greatly appreciated.

 

[JohnC]

Good that you've checked for spark and timing. Are you sure the TDC mark is accurate? Some move with age. I see you've got a pulse in each injector line but do you have a cone spray from each injector? And have you balanced the butterflies? And made sure that the fuel enrichment lever closes when the choke is in? And that there's no leak in the vacuum side of the MU? If you haven't then you should. Otherwise you're off on a wild bunny hunt. There's plenty of guidance in this forum on all the above.

Take heart though - these cars are pretty agricultural and simple to keep in shape. But if one neglects them then one can expect to have to go back to basics on the ignition and injection systems to get them running well again. Once set up they need very little fiddling.

JC

[Waldi]

If your block is a CP-block (stamped number on LHS), it should be flat.

If you have not started dismantling I would flush the block and radiator first with a waterhose (or a cooland cleaner and let it run warm) and then do a test to confirm you have combustibles in the cooling system.

Later blocks are “recessed”.

Waldi

[Kevo_6]

Hi TRG65
Recessed blocks started from CP75001, so later cp cars came with the recessed block/gasket identified by a tag on the gasket at the rear of the block near the bulkhead.

I see you mention your car is a 1970 CP so it should be a flat block but it would be better to tell us the engine number just incase it has been changed at some time.

Advice above should be checked as it’s good advise, also check the oil for coolant etc.

 

P.S. welcome to TR6 ownership and to the forum.

Edited September 14, 2024 by Kevo_6

[trg65]

8 hours ago, JohnC said:

Good that you've checked for spark and timing. Are you sure the TDC mark is accurate? Some move with age. I see you've got a pulse in each injector line but do you have a cone spray from each injector? And have you balanced the butterflies? And made sure that the fuel enrichment lever closes when the choke is in? And that there's no leak in the vacuum side of the MU? If you haven't then you should. Otherwise you're off on a wild bunny hunt. There's plenty of guidance in this forum on all the above.

Take heart though - these cars are pretty agricultural and simple to keep in shape. But if one neglects them then one can expect to have to go back to basics on the ignition and injection systems to get them running well again. Once set up they need very little fiddling.

JC

Hello,

Checked ,Timing i tried advancing and retarding no luck, the enrichment lever in the off position. air leak I was thinking on those lines but the only air leak could be inlet manifold gaskets but taken them off no signs of leaks 

Thank you for suggestions

[JohnC]

7 minutes ago, trg65 said:

he only air leak could be inlet manifold gaskets

There's also a possibility of the vacuum hose leaking between throttle body & MU or the MU (technically CU) diaphragm leaking. A tongue check will tell you. How about balancing butterflies? Just seems a bit drastic to heave the head off if you haven't ruled out other possibilities. Of course oil in the coolant (or water in the oil - have you dropped the sump?) is a bit of a giveaway. Not sure if that's what your "froth" is...

JC

Edited September 14, 2024 by JohnC

[trg65]

Thank you for accepting me and Daphne,

 yes i did flush cooling system with hose refilled with blue antifreeze , I not sure if balancing butterflies have any influence above 1/4 throttle altho the spindles do have some play Tried the tongue test passed, all valid points, maybe i missed something not sure,

How can I check the MU if possibly culprit and rule it out.

Thank you for all the suggestions 

[Mk2 Chopper]

Have you checked you get a good spark at every plug? Is the cap okay and rotor (don't use one with a rivet, only Distributor Doctor one)?

Are the plug leads in the correct order, are the injectors in the correct order? 

What do the plugs look like after being run? Sooty, wet etc? 

Gareth

[RobH]

13 hours ago, trg65 said:

Lumenition already fitted, new plugs,  all leads newish, strong spark,timing 10 degrees

You seem to have dismissed any further likelihood of an ignition problem.

It is not unknown for electronic ignition systems to give problems.  A visible spark in the open air doesn't eliminate a problem when the plugs  are in the engine and under pressure.  What rotor arm is fitted? There are some duff ones on sale and it is usually recommended to buy from the Distributor Doctor.  Have you looked for electrical 'tracking' on external surfaces by running the engine in the dark?

What are the connections like at the coil LT terminals? Again- something that can happen is broken wires inside the insulation close to a spade connector, which gives intermittent contact under vibration. 

Edited September 14, 2024 by RobH

[trchris]

Your more than half way to removing the head so l would continue and finish that particular job then you can clean all the block water jackets properly just a heads up sometimes the manifold studs are too far in in so as to pinch the head studs which makes removing the head almost impossible until they are removed

Chris 

[John L]

You can get an air leak around the injectors, with the engine running pull out each injector and see what sort of spray you have, poke it into a jam jar to minimise the amount of fuel spray, and feel how much pull you on the injectors, may indicate a not so good o ring seal.

It might be worth checking the amount of can lift for each valve, I know the cam lobes do loose a bit of height,  I not sure which ones but I have a feeling its some at the front and rear, because of reduced oil flow/splash to them, but other guys may be more specific, I had this on my 5, a new cam made all the difference to the even running of the engine.

John

Edited September 14, 2024 by John L

[trg65]

Strong spark on each plug used a spark tester , also measured the resistance on leads 1.8 oms 2.00 oms 

Plugs are new but get sooted up, tried colour tune but  hit and miss, not sure what to do,now i've  started so i'll continue to remove head have the exhaust seats unleaded fi not already done? i'll keep everyone posted,

Any suggestions on MU Diagnosing mixture strength etc.?

wife keeps asking what wrong with Daphne 

Many thanks for replies

 

[TR NIALL]

Neil Ferguson in Stafford would be the man for MU problems and a refurb Id also be advancing the Timing to 14/16 as 10 Degrees is as far as I’m concerned to retarded.

[andyhall]

Hi, years ago I had a miss fire on a Peugeot 504, was fine at lower revs only did it under power, tried everything, then pulled the head, turned out to be a burnt inlet valve.

Just a thought 

Andy

[trg65]

Its had new plugs DD rotor arm, cap,Tried the Suck test on MU vacuum all good, as far as the ignition am quite sure it's ok could be wrong,

Having removed the now, looked at cam follower's some badly pitted also rocker arm faces  tops of valve stems,seems as this has been overhauled but not to good standard,Exchange injectors from N Ferguson, couldn't upload any more pictures files to large

different caps on exhaust to inlet?

I Am thinking MU Knackered

lil Take head to machine shop the only one i know off   Bromsgrove engineering

[BlueTR3A-5EKT]

Yes the inlet and exhaust spring retaining caps are different 

[trg65]

Thank you

[BlueTR3A-5EKT]

Somewhere else to get the head overhauled 

http://www.peter-burgess.com/mobilepage.html

 

[trg65]

Thank you 

[Richard71]

Re your photo of the cyl head, does anyone know if the difference in height between ex & In valve stems is typical of our TR6 heads?

My cylinder head has a similar difference. When the head was last worked on, Peter Burgess thought this was a mistake made on a previous re-work and that perhaps the seats were cut far too deep. 

Richard. 

[trg65]

That’s my thinking as well hope my cylinder not scrap

[BlueTR3A-5EKT]

17 minutes ago, trg65 said:

That’s my thinking as well hope my cylinder not scrap

It’s a TR so infinitely repairable 

You could also ask Chris Witor for help advice

http://chriswitor.com

 

Edited September 15, 2024 by BlueTR3A-5EKT

[Richard71]

51 minutes ago, trg65 said:

That’s my thinking as well hope my cylinder not scrap

Your head won't be scrap because of the height difference, my engine powering away no problem.

Richard. 

[trg65]

Thank you Richard

[michaeldavis39]

John what cam did you get for your Tr5 and where from? I ask as I hear all sorts of stories about poor quality camshafts.

Michael