Outer Limits 4x4 Board

Compression tested my motor on a hunch and got the following results.

Numbered from front to rear
Passangers side bank
1-130
2-125
3-125
4-130

Drivers side bank
1-130
2-135
3-115
4-135

Now that 115 has me worried although most are a little down from spec?
I was thinking that rings etc would wear evenly, or am I a fool?

could be a dodgy valve, broken ring? did you test twice and get the same readings?

Tested twice, edged up towards 120 but not quite the second time. I plan on checking again tommorrow, is the "wet test" (squirt oil in) valid in people opinion for diagnosis? and how much oil?

yeah the oil is meant to show if you have worn / broken rings? if the pressure goes up after the oil is in, then you have a ring problem. if not a valve problem.

are you using oil, blowby problem? i dont know if the 10-20 psi difference is a major concern?

using water? head gasket?

too many farken questions.

popeye wrote: are you using oil, blowby problem? i dont know if the 10-20 psi difference is a major concern?

using water? head gasket?

too many farken questions.

Water is good, have kept a close eye on it, not loosing any that I can notice.
Timing cover is leaking but my main indicator is that oil seems to come up and drip out of the dipstick tube, I would never have noticed except that it hits the exauhst and burns.

Rover v8s do not use water unless the head gasket is gone on the end cylinders. What is MOST likely is for a cylinder to leak into the valley, so oil leaks at the end gaskets ,pressure in the crankcase and low compression are the only giveaways.
Most probable reasons for low compression on one cylinder are leaky valve or head gasket leak to valley.
Regards Philip A

Philip A wrote:Rover v8s do not use water unless the head gasket is gone on the end cylinders. What is MOST likely is for a cylinder to leak into the valley, so oil leaks at the end gaskets ,pressure in the crankcase and low compression are the only giveaways.
Most probable reasons for low compression on one cylinder are leaky valve or head gasket leak to valley.
Regards Philip A

prety much spot on there. tho once my rangie got a miss i thought it had a burnt valve cause it had been running straight gas for ages. i drove over 200k before i pulled the heads and found fuck all left of number3 piston

Cheers guys, guess either way the heads will have to come off so I'll start with that and work on from there.

G`day , if you did your test with a hot engine , it won`t matter , if not you`ll get low readings .

I`d suggest you give it a wet test before you pull it apart , 4 or 5 squirts of oil in each , spin it over and do the test .

It will tell if it needs rings , if it does it`ll probly want bearings and that`s engine out .

If it says the rings are ok and it`s still got a low comp , your left with headgasket or valve or both .

As popeye said it`s only just on the border of being low , Some reckon 20psi some reckon 10% either way it`s close but of coarse it won`t improve .

The oil up the dipstick could be a few things , the simplist would be the lack of an O ring on the dipstick or a poor seal . If the engine breathers , pipes , flame traps , etc are blocked will cause pressure build up . Headgasket into the valley , as Philip said and blowby .

The other jigger that can tell a bit if you know someone that knows how to use it and read it is a Vacuum gauge .

Coarse sparkplugs can tell a bit too .

What i`m suggesting is if you work out how good or bad it is before you get it apart , you`ll be able to work out how many pesos it wants to be happy .

All the best , peter .

Pulled heads, pics below. Everything seems fine, infact looks like it had some work done not long ago. tappets and cam(what I can see) barely marked.

So are there any opinions to be offered?
If not it's going back together in the next 2 days.

G`day , its abit hard to tell from pics but the cyl near the inlet end cyl may be leaking.

What does it look like under the gaskets they leak on that side as well .

If you can see a clear sealing ring around each cylinder on each side of the gaskets and on the head surfaces and on the block surfaces they may not be leaking .

With the pistons a the top of there stroke how much flex/movement can you get from each and is it even ?

If you pull the valves out and any are leaking you should see a difference in them .

I usually hook a compressor up before dismantle if i have trouble narrowing it down with the usual . Only use low capacity comp . If the comp stops and holds pressure , good pot , if it keeps running listen at exh , inlet , sump . Tells ex valve in valve or rings .

I`ve got 4 in bits as of today , 1 has broken rings in 2 pots an 1 stuffed liner , 2 has a slipped liner and a broken main bolt , 3 has 1 gasket leaking into the valley and a round lobe on its cam ( best one ). 4 isn`t all apart but the pistons have enough movement to say the ring are sick .

cheer's I'll check the piston movement. Valves I'm not sure off, I guess I have to pull them down to check them?

G`day , shouda said if you can still hone marks in the bores ( cross hatch at angle to bores ) it possibly hasn`t done a lot of work , also if you use a scotch brite pad and rub the carbon off the very top on the bores where the rings don`t get too and you can find any sort of lip then it has done a bit of work .

From your pic i can see a shine on the cam , which indicates as you say it`s good . If you pull a couple of lifters out and put a straight edge across them as you hold it up to light , you should be able to see where the center of the lifter surface touches the straight edge and you should see light on either edge . All it tells is how much work its done , the rubbing surface being a convex shape is in good nick if it looks this way . One that is flat or concave isn`t .

While you have the top off it`s also a good time to check how acurate the timing mark for TDC is

All the best , peter .

Cheers mate appreciate the tips, first time engine stripper and all
Checked piston movement, no one has any more movement laterally than any other. less than a mm each way?

Lip is there in the cylinders, slight, can just feel it with finger nail, can't see it.
Lifters are all good as you suggested. TDC mark appears good, as in No 1 tops out there Think that is what I am looking for, should check my manual on that one .
One thing I can't seem to find in my workshop manual is weather or not too use a gasket sealent on the inlet manifold gasket. I know not too on the head gaskets, bu there is nothing for the inlet manifold, or maybe I'm just missing it.

TDC should be the top of cylinder 1 as you said.

On the same subject, I am in the middle of rebuilding my motor. The manual (old 77 model manual) says to use thread sealant on the head bolts. Is this the same as loctite or can I just use loctite? Also do I need to drive the car for a bit then again tighten up the head bolts as you did with some of the old cars?

I've never used thread sealant on my rangie's in 3 head removal and re fits, i think its more for where the bolts may go into a water jacket not to lock them in.

this is a bit of a long shot, but as everything seems ok...

i would cc the chambers. A head i am rebuilding now has a 6+ cc range from the smallest to largest chamber. This was from previous dodgy head work. i dont know how much a few cc's will affect cranking compression, but its worth checking and getting right anyway.

also while its off you might as well do a bit of port cleaning.

Simon

G`day Thonger ,

looking at your pics again and pots 6and 8 the last 2 on the drivers side look as if there could be a bit of oil about , are they ( were they wet ? i can see number 2 pot first on drivers side is dry and in your pics does the head closest to the inlet manifold belong on this side .

My concern is that you haven`t found the cause of the oil being pushed out , if what i`ve asked above is so , it could be the gasket at number 8 leaking into the valley but as i say i can`t tell from the pics .
But the rings may be the problem .

The lip isn`t great they have to do a bit of work or suck dirt .

I`d suggest you check any breathes/pipes etc actually poke something through them to be sure they`re clear . Also i see it`s a single carb so check that the breathers from the rockers are routed correctly .

The TDC thing is only a guide , the only way to check it accuratly is with a dial gauge but really only needed when fitting a cam unless dot to dot is used but that`s only an in the paddock way , not as exact .

With the valley it depends how you feel , definatly put some on the end gaskets and around the water jackets . It`s ok to put it allover the gasket but not large quantities because it oozes out and can create problems that it did`nt have also too much around the water jacket can par -block them and cause Temperature problems . Also they give less trouble if they are torqued up as per manual .


It`s also important to clean out the head bolt holes and threads , blow them out with air , screwing the bolts in will help to ge any liquid out and at the same time be sure that they easily thread in and out by hand .

Part of the reason for the sealant the manual talks about is that dry aluminium is easily bound , the sealant helps stop this and also stops anything coming up the bolt , though i`ve used and not and found little diff .

The stuff i use is GMH sealing compound , not cheap though and is just a black tarry sort of stuff like old gasket cement is .

It`s also an accepted practice to either leave the lower row of 4 head bolts on each head out or only block the holes off with them and do them up to 15/20 ftlbs .

Our has a 4.0ltr which is a 10 bolt block ( head bolts , 10 each side ) , it has 14 bolt heads but only uses 10 head bolts per side and works fine .

The reason they deleted them in the later engines is because they rooster the heads and allow them to leak into the valley .

Anything else more than happy , should say don`t do this for a living and is a lot of years since i did , know enough to get by or into trouble though .

All the best , peter .

Hope you don`t mind Thonger . It is your thread .


Adam , if the manual says to retorque then yep , i don`t and it would only apply to a tin gasket never a composite , bolt bit above .

If you haven`t already bought you cam ect already , shop around off the shelf from anywhere Rover is the most $$$ , probly have to get gaskets there though . Also you can buy the spacer or cut the teeth off a timing gear and it is the correct size also when you remove the dowel from the back of the crank cover the rear main seal very well and if suggested not do make a cover for the sensor hole .

A couple of cylinders look dodgy to me but the photos are not clear enough.
Only you can tell us whether all of the cylindrs have a complete line around them indicating a complete gasket fire ring. Any gaps or brown spots are leaks.
Have the heads skimmed by say 2 thou if using tin gaskets to give a true surface.
You cannot rertorque if you use GM sealant. I used it and didn't retorque and mine seems OK. Its purpose is to stop water leaking down the bolts and corrosion welding them to the head.
Clean all the head bolt holes with a dental pick or similar and compressed air and maybe a rag twisted on a screwdriver ( or maybe a tap if you have one) to have them totally clean RIGHT TO THE BOTTOM. Took me hours.
Use sealant Hylomar spray or Permatex on the inlet manifold, especially around the water passages, and torque it evenly.
regard s Philip A

Yes, sorry Thonger for pitching your thread, you can have it back now.

Thanks Peter for the help, and now I have just worked out who you are, it should have clicked ages ago.

Cheers guys. Yep spent quite some time cleaning out the threads on both the heads' and block.

Cylinders where not wet, but I suspect that the breathers for the rocker covers have been throwing oil into the carby, as I have found oil in side the air filter, not helping what ever problem I have.
The cylinders all appeared to have complete rings, with no staining on block head or gasket standing out. I am starting to think that the oil leak around the top and the occasional cloud of smoke where un related in that the inlet manifold gasket and end seals where average looking, and did not appear to be too well sealed, where as the oil being sucked in through the breathers via the carby were the smoke cause.

Oh yeah, doing this the week leading up to your wedding is a pain, Have to stop tomorrow afternoon or the oil stains won't be out of my hands by saturday.

peter r wrote: in your pics does the head closest to the inlet manifold belong on this side .

Closest to the manifold was pass side if that helps at all.

G`day Thonger ,

GOOD ON YA !!!!!!!!

Have a great day and forget about the Rangie . It will always ask more of you than you new Bride .

Well if that head goes on the pass side after looking at your pics some more i`d go out on a limb and say both the end pots 7 pass and 8 drive are leaking .

If after you clean the heads up they look like very good unmarked surfaces , i`d suggest because it appears that they were done not long ago that you put a straight edge along them and check they are flat with no twist , if ok you`ll have the choice of putting them on as is or getting them skimmed .

If you`d like to post some pics of the cleaned heads and block ?

I notice from your pic with the rockergear fitted that your rocker shafts don`t have the splash guards on them .

All they are is 2 plates that fit on opposite ends on top of the rocker gear ( 1 on each shaft ) and are placed where the rocker cover breathers are .
They are called splash plates and all they do is stop oil being splashed into the rocker breather hole and oil film being sucked to the intake .

Anyway all the best for saturday and hear from you post wedding ( if your still allowed )


peter .

peter r wrote:G`day Thonger ,

GOOD ON YA !!!!!!!!

Have a great day and forget about the Rangie . It will always ask more of you than you new Bride .

Well if that head goes on the pass side after looking at your pics some more i`d go out on a limb and say both the end pots 7 pass and 8 drive are leaking .

If after you clean the heads up they look like very good unmarked surfaces , i`d suggest because it appears that they were done not long ago that you put a straight edge along them and check they are flat with no twist , if ok you`ll have the choice of putting them on as is or getting them skimmed .

If you`d like to post some pics of the cleaned heads and block ?

I notice from your pic with the rockergear fitted that your rocker shafts don`t have the splash guards on them .

All they are is 2 plates that fit on opposite ends on top of the rocker gear ( 1 on each shaft ) and are placed where the rocker cover breathers are .
They are called splash plates and all they do is stop oil being splashed into the rocker breather hole and oil film being sucked to the intake .

Anyway all the best for saturday and hear from you post wedding ( if your still allowed )


peter .

Cheers mate.
Well I am pretty sure that I have followed all the tips here as best I can Flat yes, checked and cheched, and even had an independent check done. Cleaned up and gone back together, even used a torque wrench.
Sorry forgot too take photo's of anything last night/afternoon.
Finishing off today with accessories (like alternater) and will let you all know how it goes, if failure, oh well several lessons learned.

It runs, better I think initially, starts easier anyway, and it's not throwing oil and coolant all over the shop, also I brought a pair of mechanics gloves the other day for my hands, weak I know, but the other half was making threats.

Thanks again for all the tip's and check's guys, not everything was in the owners manual, post again in about 2 weeks.