Engine Woes

[simonminto]

Im not sure where to start with this but Ive been going round in circles for about a year now. Long story short, my 73 CR was finally back on the road after a 10 year, stop/start re-build around this time last year. Since then the engine has never really run right. Not the usual lumpy running with blips and flat spots due to metering unit, injectors and/or throttle butterflies, this was more like spitting and farting & blue oil smoke which lead to a hole in one of the pistons. This was loosely diagnosed as probable detonation. When the head was removed there was water in the pistons. The head was pressure tested and found to be ok. After reassembly by qualified mechanic the car went to a triumph specialist to have the timing checked/set. After this, the car ran reasonably well for a while but just never seemed to have the same pulling power i remember it having prior to the accident induced rebuild. Ive owned the car since 2004 and did around 15000 miles in it before being run in to in 2007.

Now to the specifics of the current rough running.

At low speed (up to to 45-50mph) the car runs well, smooth with no coughs etc and it idles smoothly at around 7-800 rpm. The problems start once you get up to 55/60 mph, the car seems to run out of power, it pinks horrendously and theres a rather nasty sounding popping noise as well.

Last week I noticed a knock from the engine, this was quickly dealt with by setting the valve clearances, however, whilst doing the adjustments when setting the final pair to fully open, (I think it was 6 & 9 but might be wrong) 1 of the pair seemed to be noticably less open than the other one.

I wondered if this could be down to a worn or damaged camshaft lobe. On test drive knock had disappeared but still no power under load in top gear, also upon returning home clouds of blue smoke or more likely steam began billowing out the back.

So today, I took the head off again for a look at the cam lobes and followers. Cam lobes seem ok from peering down the tappet holes. Followers themselves range from perfect to badly pitted. Very worrying though was finding the cylinders full of water again.

Im now at the point of being demented by it and unsure what to do next. The head is in my van ready to take to engine specialist for checking. My question is what else could/should I do. What could be causing the rough top end running and whilst the engine is in bits, what else should I do?

 

Thanks in advance.

[YankeeTR5]

A couple of quick thoughts from someone far from being a master mechanic: you've had your head checked, but what about the deck of your block? Could be the source of the water in your cylinders? If your tappets are pitted, some badly, then its highly likely the corresponding lob on the cam has suffered as well. Have you had your distributor rebuilt, or at least checked? The bushes can wear and the springs weaken resulting in bouncing timing.

 

I'm sure wiser people will chime in, but those are the things that popped to mind after reading your posts. Best of luck figuring things out. It can be frustrating but worth it in the end.

[simonminto]

Thanks Yankee,

Yes block check is on the cards. Im hoping to find someone who can do that without lifting the engine out. Although that would make for a convenient time to change a squealing clutch release bearing.

As for the dizzy, no, its never been looked at. Ive never really got my head around how s distributor work but am I right in thinking if the springs are tired and sloppy the the timing at higher revs will be out?

Youre right about the frustration but Im WAY too far in to this to give up now.

[Steves_TR6]

Stick with ot Simon!

 

Theses engines are not complex, so an experienced triumph engine builder should be able to identify and resolve the issue promptly.

 

As it has failed again so soon do you have recourse with whoever built it last time?

 

Whereabouts are you?

 

Steve

[RogerH]

Hi Simon,

I'm not a 6 pot person, I have a 4A, but somethings are similar.

A dodgy lobe will/may run OK(ish) at low revs but do not work efficiently at higher revs.

Because of your pitted followers I would take the cam out and check the lobes carefully. Also check the valve springs for binding.

 

If the rocker arms show different lift on the odd lobe or two then that is a big clue.

 

As above, check the flatness of the block face but also check the bores for any splits into the water jacket.

Make sure you have the correct head gasket - there are various block designs and associated gaskets - fitted the corrected way.

 

Take the engine out and get it done properly - and sort the clutch.

 

Roger

[Andy Moltu]

Assuming your fuel isn't contaminated with diesel it's time for a compression check to identify the culprit area: If it is low on one cylinder you will be taking the head off anyway so easy to check the cam at that time.

 

If it is steam it sounds like you may have blown a head gasket again or possibly have a water leak into the combustion chamber could be from the head or even the block. If it stood for 10 years corrosion might have holed the water jacket.
If it is blue smoke you might have holed another piston.

 

Did they check the fuel pressure? That running out of oomph at higher revs could be fuel related - possibly a stuck PRV or a pump that's shot - able to deliver sufficient fuel at low revs but not at higher loads and might prove enough to damage a piston.

[astontr6]

I do not know if this helps. My engine lasted 44 years from new, and started to die the year before with loss of power above 2500 RPM, but had reasonable compression. Then I noticed a knocking noise when cold which went when hot. This was put down to piston slap. Engine was taken out and completely stripped down. Mileage was 96K. The pistons were badly worn, but not the bores! After a re-bore, new pistons, re -ground crank, new cam shaft + followers and fully balanced etc. This engine has never before run so well? Is your engine original or has it been fully re- built sometime in the past? Lastly water in the bores ? Are any of the valve heads white as this is often a sign that water is entering the bores?

 

Bruce.

[Peter Cobbold]

A holed pisotn could also be from hyraulicing on water leaked by head gasket.

The lack of power and pinking above 60mpg, ca 3000 rpm suggests spark timing too advanced.

Detonation would need it to be too advanced.

I'd check the advance curve with a strobe light [ Caution: beware fan blades hitting hand.]

A photo of the holed piston crown might decide between hyraulicng/detonation or preignition.

A head that has been skimmed to an excessivelt high comprat could make stock timing way too advanced.

measure head thickness to get rough idea of cr or better burette it:

http://www.goodparts.com/tech_docs/TR6_Compression_Ratio.html

 

 

If 99 RON fuel helpr it run aboove 3000 rpm then suspect comprat and spark timing.

Peter

Edited July 23, 2018 by Peter Cobbold

[lightningburns]

Simon,

 

Sounds like you have more than one issue, it's a case of tackling each in turn, firstly you say you have taken the head off again, so you cant do a compression test, which would have been ideal. Get the head checked by the engine specialist, probably worth fitting hardened valve seats for unleaded fuel while they are at it.

Water in the bores, how many had water in them, did you drain the water from the block and rad before removing the head, are you sure the water did not enter the bores when removing the head, if you had significant water in the bores with the engine assembled I would think that you would get hydraulic lock and the engine would not turn over if left for say 1/2 hr after running, but you say it ran ok at low revs.

Was it overheating.

 

Regards,

 

John

[RogerH]

Regarding the 'pinking' and occasional blue smoke.

 

Oil in the air/fuel mixture will considerably lower the octane rating and so may cause pinking in an otherwise well set up engine.

 

Roger

[Nick Jones]

Re the cylinders full of water after removing the head, are you fully draining the cooling system, including using the block drain, before pulling the head off?

 

Otherwise the water you are seeing may be coming from the dismantling process rather than representing anything to do with the failure.

 

If you are getting repeated HGF then need to check that the correct gasket is being used dependent on whether you have a recessed or non-recessed block (CR would have been recessed from the factory so you head gasket should have a tab on it).

 

Other things to check re. the pinking are:

 

Measure the head thickness. If it's been over-skimmed the compression ratio may now be too high

 

Check that the distributor distributor is the correct one and that the advance/retard mechanisms are working properly.

 

Re the cam/followers, I generally assume that any cam lobe working with a damaged follower will itself be damaged. The standard CR cam is fairly prone to eating followers and lobes. Typically the very front and very rear (both exhaust valves) suffer first though this isn't always the case. An exhaust valve with nearly no lift left can lead to all kinds of strange problems.

 

Nick

[simonminto]

Wow,

Thanks for the replies everyone, I need to digest it all and make a plan. For starters, I intended to do a compression test before lifting the head but just got stuck in and forgot until it was too late. Re. Recessed/non recessed block, Im not sure whether the engine is original or not but doubt if its been touched prior to me buying the car in 2004. I know that a CR car should have recessed block but how do you you identify the difference. The number stamped on the block is CR1838HE and commission number is CR21440.

The water in the block was probably me not fully draining the system. I only drained the system from the bottom radiator hose. There is no indication of overheating on the temp gauge but Ive had doubts about how clear the waterways in the block actually are after standing for so long so I do plan to remove the plugs have a poke around and give it a good blast through. Advice here would be appreciated.

For clarity the current pistons are fine and have no holes. I never actually saw the hole in the original piston and only had my mechanics word that it was likely caused by detonation. However, I didnt mention this on my original post as Ive just remembered, at the Triumph specialist he checked fuel pressure and due to stuck prv the pressure was way high (around 160psi)

During the last partial rebuild the valve guides were replaced as well as hardened valve seats fitting. I was told the head was lightly scimmed looking at the surface Im not convinced. I dont have a suitable vernier calliper but using a steel rule the head from bottom to top surface measures 86.5mm if that helps. In addition, all pistons were replaced to achieve matching weights and the shell bearings renewed as well.

Somebody asked if I have any recourse with the person who did the last work but to be honest there were 3 companies involved and I cant be bothered with an argument about where the problem lies and whos to blame. To be honest, it could be a combination of camshaft and timing anyway and therefore nothing to do with what was done last year.

I wish I had the funds to give it to a Triumph engine specialist and tell them to sort it... but I dont and also, Id really like to sort it myself if I can, so I will read and digest all the brilliant advice above and make a plan.

Watch this space. I wont be giving up though.????

[Peter Cobbold]

Head is clsoe to original thickness and CompRat.

Running really rich wont make it detonate, but preigntion from soot in combustion chamber might hole a piston.

Differenr gaskets are needed for recessed heads, identified by a tag at the rear.

Peter

[simonminto]

Thanks Peter,

Ive heard of and seen tabs at the rear of the gasket, but that doesnt help me identify which block I have. Do you mean that there should be a tab at the rear of the block if its recessed? If so, what does it look like and where would it be. Surely the block number would be the best way to identify which is in my car.

[DaveN]

You state the engine no. starts with CR so you need a gasket with a tab at the back!

 

Dave

Edited July 23, 2018 by DaveN

[simonminto]

Thanks Dave,

Id guessed as much, but I learned long ago not to make assumptions based on logic like that ????

[DaveN]

While you have the head off. Turn it upside down and fill the combustion chambers with paraffin, it should ideally not leak away! If it does say overnight it’s time to lap the valves in.

I would suspect the camshaft if the followers were badly pitted.

Reading your original post again I think more than likely the timing was way out.

[Peter Cobbold]

Thanks Peter,

Ive heard of and seen tabs at the rear of the gasket, but that doesnt help me identify which block I have. Do you mean that there should be a tab at the rear of the block if its recessed? If so, what does it look like and where would it be. Surely the block number would be the best way to identify which is in my car.

The number stamped on the block above the MU is in the CR series, which are recessed blocks. They must be fitted with a gasket that has a tab that you should see at the rear of the engine projecting above the flywheel housing, below the battery tray.

If the gasket has nto got a tag there's your problem, no presure seal around the bores, water everywhere.....

Peter

[Peter Cobbold]

Thanks Dave,

Id guessed as much, but I learned long ago not to make assumptions based on logic like that

Dave is correct.

Peter

[simonminto]

Thanks Peter,

Apologies if Id confused matters with my description. The cars had 3 head gaskets over the last 18 months. All have been recessed block gaskets (with a tab) I have ordered these specifically because its s CR car and therefore as you confirmed should have a recessed block.

I was asking only what the visual differences are between a recessed block and an earlier non recessed block because Id begun to suspect it may not be the original engine.

As an example of why Im suspicious... It has no ballast resistor so it uses a 12v coil.

[Peter Cobbold]

Thanks Peter,

Apologies if Id confused matters with my description. The cars had 3 head gaskets over the last 18 months. All have been recessed block gaskets (with a tab) I have ordered these specifically because its s CR car and therefore as you confirmed should have a recessed block.

I was asking only what the visual differences are between a recessed block and an earlier non recessed block because Id begun to suspect it may not be the original engine.

As an example of why Im suspicious... It has no ballast resistor so it uses a 12v coil.

The number stamped on the block should identify it. Highly unlikely anyoen has tampered with that.

The gasket is fitted to clean dry surfaces - no goo.

Peter

[Andy Moltu]

They don’t have ballast resistor as such the resistor is built into the wire.

 

If you fit a tabbed (CR) gasket to a Non recessed block (CP) water will piddle out when you fill it as the gasket won’t seal properly as there is no groove for the thicker gasket rings that surround the cylinders to sit in.

 

You can fit a CP flat gasket to a recessed block but it will blow pretty quickly.

[John McCormack]

My car is a CP with CP internals and head but a CR block. I assume I need the tabbed gasket?

[elclem1]

Not wishing to spoil the engine party but did you check that the MU choke cable was returning to zero once the choke was pushed in? I had one that the inner cable was too long and was hitting the battery and leaving the MU slightly over fuelling not that noticeable at low revs but try and pull away it ran like a tractor, lots of smoke and farting not good when trying to impress people, The plugs soon sooted up and here begineth the lesson- PI !!! Just a thought - clem

[Peter Cobbold]

My car is a CP with CP internals and head but a CR block. I assume I need the tabbed gasket?

Yes, tabbed for CR blocks. Heads are interchangeable CP <> CR ( but manifolds changed at some point)

Peter