causes of low cylinder compression in a td42

Post by **patrolla** » Mon Apr 20, 2009 7:21 pm

i've just had a compression test done on the cylinders and it's running factory spec on cylinders 1-4, with slightly below on cylinder 5 and quite a bit below on cylinder 6. has done 320,000km and is an '88 model.

what could be the possible causes or is that asking how long's a piece of string?

Post by **Z()LTAN** » Mon Apr 20, 2009 7:46 pm

Post by **jet-6** » Mon Apr 20, 2009 7:59 pm

2 bent rods

Post by **Z()LTAN** » Mon Apr 20, 2009 8:10 pm

nah mate, the rings on 5-6 are worn out.

Its not uncommon for the rings to wear out non uniformly.

Post by **busman** » Mon Apr 20, 2009 9:01 pm

Get a leak down test done to see if it's rings or valves or both.

Post by **mavzilla** » Tue Apr 21, 2009 10:47 pm

been through water and bent no 5&6 rod my guess , very common

Post by **Z()LTAN** » Tue Apr 21, 2009 11:03 pm

lol u can tell if its got a bent rod... what with all the clakking and white smoke...

Post by **heathhoppy** » Tue Apr 21, 2009 11:37 pm

patrolla wrote:i've just had a compression test done on the cylinders and it's running factory spec on cylinders 1-4, with slightly below on cylinder 5 and quite a bit below on cylinder 6. has done 320,000km and is an '88 model.

what could be the possible causes or is that asking how long's a piece of string?

maybe worn out had dirty air cleaner services not up to date the list could go on and on

Post by **patrolla** » Wed Apr 22, 2009 11:13 am

so i got the compression readings:
1-4 = 500
5 = 450
6 = 475

apparently those readings are all above spec but 5 and 6 should be a little higher in an ideal world. still no issues turbo-ing on those readings, according to diesel tech in lilydale.

Post by **Z()LTAN** » Wed Apr 22, 2009 12:12 pm

yeah thats not down all that far.

Youll be looking at a ring and bearing kit at some time in the future no doubt.

Post by **WOZ** » Wed Apr 22, 2009 12:41 pm

I would be checking the tappet clearence. Its only down 10% of its compression on those cyls. I get a lot of td42s in my shop that are sluggish until the tappets are adjusted. If you are concerned about engine condition, have a proper leak-down test done, if its about 20% or less the engine is fine. Hope this helps.

Post by **patrolla** » Wed Apr 22, 2009 1:54 pm

yeah, my mechanic (who's not a diesel specialist but still pretty good) said it is a bit "tappety".....considering the ring and valve leak tests as well as tappet adjustment.

Post by **PGS 4WD** » Wed Apr 22, 2009 8:13 pm

If the cylinders are side by side (5&6) it is common for the head gasket to blow between cylinders, it could be tight valves, worn rings, bent rods and all the ther mentioned things too.

Joel

Post by **patrolla** » Thu Apr 23, 2009 9:14 am

but if it's not using any water, it wouldn't be head gaskets would it? and what if it did use a small amount of water, hypothetically?

Post by **Troll00** » Sun Apr 26, 2009 10:42 pm

My GU with 290k on the clock had 180 in #2 and 380 in some and the best was 450, had a cracked head stuffed bores, pistions, rings etc etc

Still doing the rebuild

Outer Limits 4x4 Board

causes of low cylinder compression in a td42

causes of low cylinder compression in a td42

causes of low compression

Re: causes of low cylinder compression in a td42

Who is online