Compression test :: Triumph Torque

Moordale Motors

Welcome, Guest.
Please login or register.
Compression test
Forum Login
Login Name: Create a new account
Password:     Forgot password

Triumph Torque    Cars    2000/2500/2.5PI  ›  Compression test
Users Browsing Forum
flap, Yahoo! Bot and 14 Guests

Compression test Print
1 Pages 1 Recommend Thread
gilesdive
November 11, 2006, 1:00pm Report to Moderator


Posts: 1,432
Posts Per Day: 0.48
Hi folks
Just want to pick your brains for a minute. On a 2500 engine (mine is a PI unit in a TR6, CR,  125 bhp version) roughly what should I expect if I put a compression tester on it?

Just cranking it over, I am getting between 70 and 90 psi. There is a bit of a spread of readings there, but do you think they are generally too low? I was advised by one chap they should be well into 3 figures - is this so? If that's the case, head off.

Thanks


White 1974 TR6 is "toy" car for evenings & weekends only.
Used to drive Spitfires as main transport, but have a eurobox for work these days.
Don't believe in putting the roof up - a bit of snow never hurt anyone! Get the Biggles jacket out

Location: West Yorkshire
Logged
Private Message
Nick Jones
November 11, 2006, 2:23pm Report to Moderator

Club Member
Posts: 7,256
Posts Per Day: 2.13
Sounds a bit low to me - I would have thought 140 - 180 ish/  Ideally to be equal within 10psi.

Are you doing this with throttle open or closed?  This can make a difference - should be open.

Putting around a table-spoonful of oil into each bore will temporarily improve the ring seal and help determine whether this is a valve or bore issue.

If the engine is an ex-US detox thing they have very low compression ratio so your readings may not be too far off what they should be.

Nick


Nick Jones
Somerset UK

Vitesse Mk 1.5 Convertible EFI, Survivor of RBRR 2008, HCR & 10CR 2009, HCR 2010, 10CR2011, HCR 2012 & 10CR2013.
2.5 PI Saloon now EFI (PIe?), Engine rebuilt and running sweet.  Diff howling...... Survivor of HCR 2013 & 2014 Gone to live in Swansea

http://www.tengaston.plus.com
Logged
Private Message Reply: 1 - 9
gilesdive
November 11, 2006, 3:24pm Report to Moderator


Posts: 1,432
Posts Per Day: 0.48
Ah, did it with throttle closed.
It is not an ex-USA car, it is to UK spec.
Fairly sure it's not piston rings/bores as harly any smoke when it was last running.

Bad news is I have taken back compression tester (only borrowed it) - but not sounding good is it?

Thanks for the quick answer though.


White 1974 TR6 is "toy" car for evenings & weekends only.
Used to drive Spitfires as main transport, but have a eurobox for work these days.
Don't believe in putting the roof up - a bit of snow never hurt anyone! Get the Biggles jacket out

Location: West Yorkshire
Logged
Private Message Reply: 2 - 9
davesideways
November 11, 2006, 7:24pm Report to Moderator
Guest User
post removed on request of author



Logged
E-mail Reply: 3 - 9
gilesdive
November 13, 2006, 3:27pm Report to Moderator


Posts: 1,432
Posts Per Day: 0.48
Thanks for those details. I have had to shell out for a guage as the one I borrowed is no longer available - will be able to check it with throttles open next weekend, at least I know what it should be.


White 1974 TR6 is "toy" car for evenings & weekends only.
Used to drive Spitfires as main transport, but have a eurobox for work these days.
Don't believe in putting the roof up - a bit of snow never hurt anyone! Get the Biggles jacket out

Location: West Yorkshire
Logged
Private Message Reply: 4 - 9
Richard B
November 13, 2006, 3:50pm Report to Moderator

Moderator
Administrator
Posts: 12,279
Posts Per Day: 3.15
Good luck, also do a dry test followed by a wet test (add a drop of engine oil). I there is a significant improvement suspect Piston Rings. 


Surrey AO and Triumph Hoover,Location: Guildford - Surrey,

Spitfire 2.5PI - 1967, PI Saloon - 1969, PI Saloon MkII - 1971(stalled project),PI Estate - 1969 (to restore)
Stag - 1971, Custody of :MkII2000 Estate - 1973 (my wife's)
Daughters own: Herald 1500 -1961, Herald 1200 Coup 1962, Dolomite 1300 - 1976

"When you were sitting in that capsule listening to the count-down, how did you feel?" Well, the answer to that one is easy. I felt exactly how you would feel if you were getting ready to launch and knew you were sitting on top of two million parts -- all built by the lowest bidder on a government contract. - John Glenn
Logged
Private Message Reply: 5 - 9
Freebird
November 14, 2006, 6:06pm Report to Moderator


Posts: 1,595
Posts Per Day: 0.51
Before I rebuilt my 2.5, the compression on number 1 was 7 bar - about 105 PSI with the throttle wide open, all the others were about 140 - 150 PSI. It had a CR of 8.5-1

Both top piston rings on No1 were stuck in their grooves, breaking up on pushing them past the big step in the bore (or broken already). A 20 thou rebore just about cleaned up the wear which was much the same in all bores - that's how bad it was. It didn,t actually smoke much even when cold, the oil control rings were all intact.

As Dave says 70-90 really doesn't sound right.

Glen.


'69 Vitesse Convertible 2500
'78 Spitfire 1500 - Gone to No1 son (only one actually) Joe
'01 MG ZT-T for daily use and abuse
'03 Citroen Picasso for eldest step daughter - bound to go wrong
'97 Corsa for the younger one. - seems indestructable.

'81 Laverda 3CL
'82 Moto Guzzi 850 rat bike
'99 Triumph Sprint Sport 900

Location: Merstham, Surrey.
Logged
Private Message Reply: 6 - 9
JohnD
November 14, 2006, 8:55pm Report to Moderator


Posts: 5,039
Posts Per Day: 1.47
Compression testers are NOT precision instruments!
So the absolute pressure shown by each tester may not compare, other than 'ball-park' .
Far more important than absolute pressure is that all cylinders should be the same.
Suspect any that aren't.
If the oil test doesn't improve pressure, then suspect the valves.

John
Logged Online
Private Message Reply: 7 - 9
gilesdive
November 26, 2006, 12:00pm Report to Moderator


Posts: 1,432
Posts Per Day: 0.48
Been a slight delay in getting this done (illness / work) but finally did compression check with throttles fully open - yes, a big difference.
Lowest one was 165 psi and the highest about 175-180, that was without any oil in the bores.
Good news, this suggests valves and piston rings ok, don't need to pull the head off.
All I need now is to actually get it going!


White 1974 TR6 is "toy" car for evenings & weekends only.
Used to drive Spitfires as main transport, but have a eurobox for work these days.
Don't believe in putting the roof up - a bit of snow never hurt anyone! Get the Biggles jacket out

Location: West Yorkshire
Logged
Private Message Reply: 8 - 9
Nick Jones
November 26, 2006, 3:29pm Report to Moderator

Club Member
Posts: 7,256
Posts Per Day: 2.13
That sounds pretty good, especially if done cold.  Normally improve a bit when warm.

Nick


Nick Jones
Somerset UK

Vitesse Mk 1.5 Convertible EFI, Survivor of RBRR 2008, HCR & 10CR 2009, HCR 2010, 10CR2011, HCR 2012 & 10CR2013.
2.5 PI Saloon now EFI (PIe?), Engine rebuilt and running sweet.  Diff howling...... Survivor of HCR 2013 & 2014 Gone to live in Swansea

http://www.tengaston.plus.com
Logged
Private Message Reply: 9 - 9
1 Pages 1 Recommend Thread
Print

Triumph Torque    Cars    2000/2500/2.5PI  ›  Compression test

Thread Rating
There is currently no rating for this thread
 


Powered by E-Blah Forum Software 10.3.5 © 2001-2008

Latest Blogs-
Martin Randle

20th December 2014 2:47pm gmt
Clutching at straws
Steve Weblin

19th December 2014 5:55pm gmt
TR7 Daytona replica by Robin Hood Engineering
more blogs...
Next Group Meetings-
more local groups...
Upcoming Events-
CT Dutch Rally
14th March 2015
CT Historic Counties Run
18th-19th April 2015
CT Rally
10th May 2015
International Auto Ecosse
6th-7th June 2015
CT Historic Autosolo
19th July 2015
CT Northern Tour
8th-9th August 2015
more events...
For Sale-
4 winter tyres 195/60R15 on Ford steel rims 6mm tread.£100 Ford roof rack for Ford Fusion.£40 collect only. Contact Kevin 07946700004. location Essex/M25

Spitfire 1500 in Brooklands Green/Black. Owned 15 yrs, fully restored 10 yrs ago, stored for last 9 yrs, just MoT’d again. 5.5J GT6 wheels, fast road spec engine, 2004 CT valuation £5,600, OIRO £5,300, Tel Dave on 07956 487643, North London

Herald Convertible 6547 DT loads of spares numerous steering racks, suspensions,spri ngs,even twin tanks - brand new 4.11 diff assy incl reg number. contact jrarmstrong@btin ternet.com for complete list otherwise will scrap

more adverts...
CLUB TRIUMPH the Club for all Triumphs
© Club Triumph Ltd MCMXCVI - MMXIV