Discussion
I have never heard of piston slap being a problem with Esprits, in the roughly 3 years I have been involved with them. Actually, I have never heard of piston slap being a problem with any motor that was rebuilt properly. Ask them what the piston clearance was when they put it together, and how they explain "piston slap" in a fresh motor. It probably is the valves not adjusted properly, like you thought, and they are trying to BS you into just going away.
I had a shop charge me a lot of money (at the time) for a rebuild on my Europa. I don't think they even took the head apart. I asked them where they got the valve shims and they said they didn't need any. They screwed the motor up so bad that (sitting there with what was left of #3 piston in my hand) I figured I could screw it up just as well for a whole lot less, and I have been doing all my own work since.
Bring it back and tell them to fix it under warranty, and in a timely fashion.
I had a shop charge me a lot of money (at the time) for a rebuild on my Europa. I don't think they even took the head apart. I asked them where they got the valve shims and they said they didn't need any. They screwed the motor up so bad that (sitting there with what was left of #3 piston in my hand) I figured I could screw it up just as well for a whole lot less, and I have been doing all my own work since.
Bring it back and tell them to fix it under warranty, and in a timely fashion.
My car had an interesting metallic tinkle at about 2100-2300 rpm that I initially thought was piston slap. Then I decided it might be the tensioner bearing, then I thought it might be something just rattling harmonically.
Turned out that two of the pistons had broken up; guess it was kind of 'slap'...
Turned out that two of the pistons had broken up; guess it was kind of 'slap'...
You should have gotten a brand new engine for that amount and then some... certain brands of forged pistons run very high tolerances in order to account for expansion. This results in piston slap as the pistons slosh around in the cylinder until they reach proper temps. This isnt something that could be fixed or adjusted, just a result of the piston choice.
It's really hard to comment on what you are hearing without hearing. But assuming for the moment that it is piston slap, here are a few thoughts.
What vintage Turbo. Early low compression Turbo's used iron liners and aluminum pistons... two metals with significantly different coefficients of thermal expansion. In order for the pistons to have the correct clearances at full normal operating temperature, the clearances had to be very loose when cold. The engines can sound down right agricultural when cold but quiet down as they come up to temp. Does your noise become more tolerable as the engine warms up?
The pistons also use an offset gudgeon pin (wrist pin) to help minimize piston slap with the wide clearances. That makes the pistons directional and they must be installed correctly. As an assembly aid, the pistons are marked to indicate which side faces the front of the engine. If the pistons were installed backwards, piston slap would be worse than normal.
The early low compression engines used cast aluminum pistons. Cast pistons continue to shrink slowly and the diameter can become measurably smaller. Combined with cylinder bore wear, clearances can become significantly larger. "IF" the old cast pistons were used with the original liners, clearances could easily be off the loose end of the spec, and a sloppy fit would result in more piston slap.
If you have a high compression engine with Nikasil liners, then clearance spec's are much tighter. There are rarely piston slap issues in 910HC engines that are within spec.
Gudgeon Pin Bore Offset:
907 Std 1.52mm (0.060 inch) towards thrust face
907 H-C 1.52mm (0.060 inch) towards thrust face
912 Std 1.52mm (0.060 inch) towards thrust face
912 H-C 1.50mm (0.059 inch) towards thrust face
910 Std 1.52mm (0.060 inch) towards thrust face
910 H-C Zero
Piston Clearance in Cylinder Liner
907 Std 0.10/ 0.13mm (0.004/ 0.005 inch) Iron
907 H-C 0.10/ 0.13mm (0.004/ 0.005 inch) Iron
912 Std 0.11/ 0.15mm (0.005/ 0.006 inch) Iron
912 H-C 0.05/ 0.08mm (0.002/ 0.003 inch) Nikasil
910 Std 0.11/ 0.15mm (0.005/ 0.006 inch) Iron
910 H-C 0.048/ 0.076mm (0.002/ 0.003inch) Nikasil
It's not unusual for owners to think their freshly rebuilt engines, or engines with recently adjusted valve clearances are noisier. Because they are. The valve clearances close up with wear, and tighter clearances run with less clatter. But too-tight clearances are not a good thing even if they are quiet. When the valves are shimmed back up to the high end of the specs, they run with more clatter. Despite the unattractive quality of the noise, a little clatter (appropriate to the high end of the spec range) is a good thing while a quite valve train indicates a problem.
I've also known a few owners who really didn't spend much time in the engine bay with the engine running before the re-build/ valve clearancing, and didn't have a good feel for how the engine sounded before. When they did have an occassion to hear the engine running with the bonnet open, they were concerned about the amount of general clatter that is normal.
Aahhh... £13000 !?
=8<0
Good luck,
Tim Engel
Lotus Owners Oftha North, USA
>> Edited by Esprit2 on Saturday 12th November 03:06
What vintage Turbo. Early low compression Turbo's used iron liners and aluminum pistons... two metals with significantly different coefficients of thermal expansion. In order for the pistons to have the correct clearances at full normal operating temperature, the clearances had to be very loose when cold. The engines can sound down right agricultural when cold but quiet down as they come up to temp. Does your noise become more tolerable as the engine warms up?
The pistons also use an offset gudgeon pin (wrist pin) to help minimize piston slap with the wide clearances. That makes the pistons directional and they must be installed correctly. As an assembly aid, the pistons are marked to indicate which side faces the front of the engine. If the pistons were installed backwards, piston slap would be worse than normal.
The early low compression engines used cast aluminum pistons. Cast pistons continue to shrink slowly and the diameter can become measurably smaller. Combined with cylinder bore wear, clearances can become significantly larger. "IF" the old cast pistons were used with the original liners, clearances could easily be off the loose end of the spec, and a sloppy fit would result in more piston slap.
If you have a high compression engine with Nikasil liners, then clearance spec's are much tighter. There are rarely piston slap issues in 910HC engines that are within spec.
Gudgeon Pin Bore Offset:
907 Std 1.52mm (0.060 inch) towards thrust face
907 H-C 1.52mm (0.060 inch) towards thrust face
912 Std 1.52mm (0.060 inch) towards thrust face
912 H-C 1.50mm (0.059 inch) towards thrust face
910 Std 1.52mm (0.060 inch) towards thrust face
910 H-C Zero
Piston Clearance in Cylinder Liner
907 Std 0.10/ 0.13mm (0.004/ 0.005 inch) Iron
907 H-C 0.10/ 0.13mm (0.004/ 0.005 inch) Iron
912 Std 0.11/ 0.15mm (0.005/ 0.006 inch) Iron
912 H-C 0.05/ 0.08mm (0.002/ 0.003 inch) Nikasil
910 Std 0.11/ 0.15mm (0.005/ 0.006 inch) Iron
910 H-C 0.048/ 0.076mm (0.002/ 0.003inch) Nikasil
It's not unusual for owners to think their freshly rebuilt engines, or engines with recently adjusted valve clearances are noisier. Because they are. The valve clearances close up with wear, and tighter clearances run with less clatter. But too-tight clearances are not a good thing even if they are quiet. When the valves are shimmed back up to the high end of the specs, they run with more clatter. Despite the unattractive quality of the noise, a little clatter (appropriate to the high end of the spec range) is a good thing while a quite valve train indicates a problem.
I've also known a few owners who really didn't spend much time in the engine bay with the engine running before the re-build/ valve clearancing, and didn't have a good feel for how the engine sounded before. When they did have an occassion to hear the engine running with the bonnet open, they were concerned about the amount of general clatter that is normal.
Aahhh... £13000 !?
=8<0
Good luck,
Tim Engel
Lotus Owners Oftha North, USA
>> Edited by Esprit2 on Saturday 12th November 03:06
I will add that on reflection, I have heard of some piston slap when cold as noted above by greezmonkey with motors that have been built to withstand extreme boost using rather exotic forged pistons. Is this what you got? And does it get much better when it warms up?
13K GBP is a bit outrageous. Cheaper to buy another car.
Dr.Hess
13K GBP is a bit outrageous. Cheaper to buy another car.
Dr.Hess
The 9xx engines in both cars I have owned have suffered piston slap (when cold) which all but disappeared when the engine was at normal temperature. One engine had done 25k (N/A 2.2 in an Esprit) and the other 80k+ in an Excel SE.
I would say it is par for the course, and nothing to worry over if it goes when the engine is hot.
The rebuild cost does seem rather excessive though.
I have seen your post on LEW, and the number of labour hours seems incredible.
Paul.
PS I have seen road tests of almost new Esprits where the testers comment on the clattery nature of the engine. One said something along the lines of 'piston slap like an old Cortina'.
>> Edited by B16 RFF on Sunday 13th November 14:07
I would say it is par for the course, and nothing to worry over if it goes when the engine is hot.
The rebuild cost does seem rather excessive though.
I have seen your post on LEW, and the number of labour hours seems incredible.
Paul.
PS I have seen road tests of almost new Esprits where the testers comment on the clattery nature of the engine. One said something along the lines of 'piston slap like an old Cortina'.
>> Edited by B16 RFF on Sunday 13th November 14:07
I also have to say that I now do most of my own work and get help from the guys in the local club when I need it due to the absolute CRAP that the shops and dealers turn out. Over and over I would find things missing from routine stuff like coolant flushes and oil changes.
One Mitzubishi dealer back in the day fubard my brake job so bad that the shop that finally did it correctly listed out "numerous parts missing"... and there was. At the time I was in school and had no place to work on the stuff myself...
As for the 9XX motors, I have read in several articles and still I have heard others say how noisy these motors are when cold... and they do not get exactly quiet when hot... I think (think) it was Motor Trend that said that the motors sounded like "a box of rocks in a tumble dryer until warmed up".
Drive topless!!!
Cameron
One Mitzubishi dealer back in the day fubard my brake job so bad that the shop that finally did it correctly listed out "numerous parts missing"... and there was. At the time I was in school and had no place to work on the stuff myself...
As for the 9XX motors, I have read in several articles and still I have heard others say how noisy these motors are when cold... and they do not get exactly quiet when hot... I think (think) it was Motor Trend that said that the motors sounded like "a box of rocks in a tumble dryer until warmed up".
Drive topless!!!
Cameron
My Excel SE (nikasil) also has what sounds like piston slap when cold but quietens down a lot when warm. It has been about the same from 50k miles to the current 132k miles!
It also seems a lot worse when the valve that advances the ignition up when cold is active - on the Excel SE, this is below about 60 degrees. As soon as the valve closes, ignition drops from 30+ deg advance to the standard 10 deg, the slap seems to disappear. I guess firing the spark so early at low revs is causing the piston to clatter around a bit - but that's how lotus designed it!
My valve gear is also a little nosier than some, but then I do set the clearances to the wide end of spec (when I adjust them) so I don't need to adjust them as often when they slowly close up!
It also seems a lot worse when the valve that advances the ignition up when cold is active - on the Excel SE, this is below about 60 degrees. As soon as the valve closes, ignition drops from 30+ deg advance to the standard 10 deg, the slap seems to disappear. I guess firing the spark so early at low revs is causing the piston to clatter around a bit - but that's how lotus designed it!
My valve gear is also a little nosier than some, but then I do set the clearances to the wide end of spec (when I adjust them) so I don't need to adjust them as often when they slowly close up!
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