I had posted here a few months about, car was misfiring, shaking and making a strange noise on acceleration. We thought could be the coil packs. I did some investigation and just nothing was working. Next step was a compression test but since its winter here and I don't currently have a garage (its feels like -19F today (-28 for my european friends) I decided to just take the car to the shop, next step was a compression test which they did. Well, no good news there, they told me cyl 5 has no compression at all. They thing its a piston or a ring. Their recommendation is a new "old" engine.

Obviously this is not going to be cheap but my problem here is putting an old engine in that might have issues soon enough. There is an engine with 92k miles available, its almost $4000. After labour we are probably looking at 7 or 8. Am I crazy but this just does not sound like a good idea, at 92k it could need HGs done amongst other things. Other option is a remanufactured engine but that jumps to $8000 + labour which atm it is not something I am willing to spend.
Rebuilding could also be an option but also not cheap and in some cases could be as much as a "new" engine if done properly.

I really love the p38 and this one is in great shape, still on air of course, body in fantastic shape, I just did all the rear brake lines myself and other bits and bobs. Am I crazy to try to do an engine replacement myself? My idea is if I do this and there are issues in a few years oh well at least I learned vs paying someone and getting nothing for it. I have never done something of this scope but I love learning, a few years ago I did not even do my own oil changes but have been replacing stuff on the p38 and just learning a lot. This would take me a long time to do and I have other cars so time is not a problem.

Or if you guys have any other ideas I would love to hear them. I probably should just let it go but I just love this thing too much,.

Thank you

If you have no compression at all, I wouldn't be looking at a piston or ring. Unless the piston has a hole in it, you would still have some compression, it would be down but there would still be something. I would suspect something in the top end, either a burnt valve (pretty unlikely) or a broken valve spring so a valve is never closing fully. I would pull the head off first, if you even need go that far, you'd see a broken valve spring as soon as you get the rocker cover off.

Depending on whether you intend doing it yourself or paying someone else to do it, even if you have a holed piston, it isn't going to be too expensive and can all be done with the engine in the car. Even an engine swap is pretty straightforward and you would only need an engine crane or something to attach a winch to so you can lift one out and drop the other one in.

Thank you for your expertise! Always appreciated.

I was told over the phone that there was no compression but just got the report and says compression on cyl 5 is 30, other cylinders 150.
They also did a leak down test and I will quote “ Had 60% leakdown through the crankcase. Suspect piston or ring damage. ”

Definitely bottom end?

Gilbertd wrote:

If you have no compression at all, I wouldn't be looking at a piston or ring. Unless the piston has a hole in it, you would still have some compression, it would be down but there would still be something. I would suspect something in the top end, either a burnt valve (pretty unlikely) or a broken valve spring so a valve is never closing fully. I would pull the head off first, if you even need go that far, you'd see a broken valve spring as soon as you get the rocker cover off.

Depending on whether you intend doing it yourself or paying someone else to do it, even if you have a holed piston, it isn't going to be too expensive and can all be done with the engine in the car. Even an engine swap is pretty straightforward and you would only need an engine crane or something to attach a winch to so you can lift one out and drop the other one in.

I would take the head off so that can be checked and then have a look at the bore for any scoring in it. It's a simple enough job to drop the sump if you jack the front of the car up so it gives lots of clearance between the bottom of the engine and the front axle. Then with the head and sump off you can pull the one piston out. If it is a piston ring and there is light scoring on the bore, that can be taken out with a hone, a new set of rings and put it back in (with new big end shells obviously).

One car I bought (a 97 4.0SE) had a similar problem on cylinder 2 which was a broken compression ring. Head off, sump off, pull that piston out, hone the bore (checking that it didn't exceed the 94.04mm maximum bore size), fit new rings, drop the piston back in and put it all back together.

If the pressure on a leak down test is leaking into the crankcase and not into the coolant passages, it isn't likely to be a leak around the liner so no need to take the engine out..

Thank you.
I have nothing to loose and do some investigation myself.

I was surprised at the suggestion of a new engine vs a rebuild myself

Gilbertd wrote:

I would take the head off so that can be checked and then have a look at the bore for any scoring in it. It's a simple enough job to drop the sump if you jack the front of the car up so it gives lots of clearance between the bottom of the engine and the front axle. Then with the head and sump off you can pull the one piston out. If it is a piston ring and there is light scoring on the bore, that can be taken out with a hone, a new set of rings and put it back in (with new big end shells obviously).

One car I bought (a 97 4.0SE) had a similar problem on cylinder 2 which was a broken compression ring. Head off, sump off, pull that piston out, hone the bore (checking that it didn't exceed the 94.04mm maximum bore size), fit new rings, drop the piston back in and put it all back together.

If the pressure on a leak down test is leaking into the crankcase and not into the coolant passages, it isn't likely to be a leak around the liner so no need to take the engine out..

Not really, think about it from their point of view. You (or they) supply a replacement engine so all that is involved is the labour involved in taking one out and putting another in compared with the labour costs of them stripping the engine and doing whatever is needed. If they have someone capable of doing it that is as most modern mechanics are simply parts fitters.

+1 on most likely it's head gasket or valve issues. I've only ever had a holed piston on an old two-stroke RD250. Never happened on any car, either me or any family members have ever owned. (>40 cars).

Gilbertd wrote:

Not really, think about it from their point of view. You (or they) supply a replacement engine so all that is involved is the labour involved in taking one out and putting another in compared with the labour costs of them stripping the engine and doing whatever is needed. If they have someone capable of doing it that is as most modern mechanics are simply parts fitters.

Totally does make sense. This is also not a land rover shop, not that they are not competent in rebuilding an engine as they do a lot of work on hot rods and stuff but compared to a shop that has been working on these for a long time.
Once again, thank you. A lot to decide but I might as well tear stuff down.
Question, is there a way for me to 100% know if its the pistons/rings? Pulling the head, would this tell me?

Pete12345 wrote:

+1 on most likely it's head gasket or valve issues. I've only ever had a holed piston on an old two-stroke RD250. Never happened on any car, either me or any family members have ever owned. (>40 cars).

With the leakdown test and 60% at crankcase would this not mean its likely bottom end?

Depends how they assessed it was leaking into crankcase ? HG towards valley would do the same, so no matter what it's head off first. Then if it's piston rings, do as said above & drop the sump.

Complete set of bottom end bearings, piston rings, gaskets & new camshaft cost me about £400-£500 a few years ago. Can you rent a workshop for a few days ? Would still be much less than that garage quote !!

Or if you definitely need to do it outside, buy a cheap run-around & wait for the warmer weather.

Pete12345 wrote:

Depends how they assessed it was leaking into crankcase ? HG towards valley would do the same, so no matter what it's head off first. Then if it's piston rings, do as said above & drop the sump.

Complete set of bottom end bearings, piston rings, gaskets & new camshaft cost me about £400-£500 a few years ago. Can you rent a workshop for a few days ? Would still be much less than that garage quote !!

Or if you definitely need to do it outside, buy a cheap run-around & wait for the warmer weather.

They said they did a leak down and air was coming through the oil filler is what I was told.

I am gonna pull the head when I can. The good thing is my “garage” which is a dirt floor is getting concrete put on in April so I will have a space to possibly do all this.

Thanks for the knowledge Pete, appreciate it

My garage has a concrete floor but it is full of another car and all my kit for doing AC installations, so no chance of working in there. It's also a standard UK sized garage so I doubt a P38 would go in it and even if it did, you'd have to crawl out the tailgate as the doors wouldn't open far enough to get out of the car. The driveway is gravel so I have some gym floor mats to lay on, thermal weatherproof overalls, thermal gloves and a tarp that can cover everything, including the car and me. Not ideal and I would really like a, at least, double width garage with enough headroom for a two post lift but that will have to wait until a lottery win comes my way (which would be difficult as I don't do the lottery....).

Gilbertd wrote:

My garage has a concrete floor but it is full of another car and all my kit for doing AC installations, so no chance of working in there. It's also a standard UK sized garage so I doubt a P38 would go in it and even if it did, you'd have to crawl out the tailgate as the doors wouldn't open far enough to get out of the car. The driveway is gravel so I have some gym floor mats to lay on, thermal weatherproof overalls, thermal gloves and a tarp that can cover everything, including the car and me. Not ideal and I would really like a, at least, double width garage with enough headroom for a two post lift but that will have to wait until a lottery win comes my way (which would be difficult as I don't do the lottery....).

I also have a gravel driveway and have been working on cars there for the past few years, also have a gym floor mat haha, works great. The "garage" is a 200 year old barn that I am finally putting some money into so will get a concrete floor and just fix all the rotten wood. Its not a super nice garage but its a huge upgrade. Its bigger than a UK standard size garage for sure (and by that I mean probably 5 times the size :) I lived in England so I know exaclty the size garage you have).

Just got the car back from the garage. Whatever they did when they were diagnosing it now in Neutral the revs stay at 4000 rpm so will have to look into that tomorrow but I guess I have bigger fish to fry

Do you have any diagnostics? Chances are the stored throttle position sensor voltage are lower than the actual voltage so it needs the adaptive values resetting.

r3awak3n wrote:

Pete12345 wrote:

Depends how they assessed it was leaking into crankcase ? HG towards valley would do the same, so no matter what it's head off first. Then if it's piston rings, do as said above & drop the sump.

Complete set of bottom end bearings, piston rings, gaskets & new camshaft cost me about £400-£500 a few years ago. Can you rent a workshop for a few days ? Would still be much less than that garage quote !!

Or if you definitely need to do it outside, buy a cheap run-around & wait for the warmer weather.

They said they did a leak down and air was coming through the oil filler is what I was told.

I am gonna pull the head when I can. The good thing is my “garage” which is a dirt floor is getting concrete put on in April so I will have a space to possibly do all this.

Thanks for the knowledge Pete, appreciate it

Air coming out of the oil filler could be from the crankcase via the oilways, but could also be leaking past a valve & up the stem.

Gilbertd wrote:

Do you have any diagnostics? Chances are the stored throttle position sensor voltage are lower than the actual voltage so it needs the adaptive values resetting.

I finally had some time to look, they left the throttle cable looped on a bolt that is in front of it, no idea why and why they did not notice this.

Pete12345 wrote:

r3awak3n wrote:

Pete12345 wrote:

Depends how they assessed it was leaking into crankcase ? HG towards valley would do the same, so no matter what it's head off first. Then if it's piston rings, do as said above & drop the sump.

Complete set of bottom end bearings, piston rings, gaskets & new camshaft cost me about £400-£500 a few years ago. Can you rent a workshop for a few days ? Would still be much less than that garage quote !!

Or if you definitely need to do it outside, buy a cheap run-around & wait for the warmer weather.

They said they did a leak down and air was coming through the oil filler is what I was told.

I am gonna pull the head when I can. The good thing is my “garage” which is a dirt floor is getting concrete put on in April so I will have a space to possibly do all this.

Thanks for the knowledge Pete, appreciate it

Air coming out of the oil filler could be from the crankcase via the oilways, but could also be leaking past a valve & up the stem.

thanks Pete. I will be be getting my hands dirty when I can and hope for the best. Not really sure what I am doing but time to learn/thats how you learn. I will pull the head to start and look around.

It's all pretty straightforward if you read through RAVE. Cylinder head bolts at 5/8" so a 16mm spark plug socket fits perfectly and is usually 6 point so you can give it a bit more grunt. Cylinder 5 is on the left hand bank (as seen from the driver's seat) so you have less space than those of us with RHD cars as you have the brake modulator on that side. The hardest part will be getting the heat shield bolts. On a RHD, the rearmost exhaust manifold bolt causes everyone grief due to getting access so I suspect the same one on the other side might cause you problems. Easiest way of getting to it is to take the inner wheelarch liner out and go at it from through the wheelarch.

Gilbertd wrote:

It's all pretty straightforward if you read through RAVE. Cylinder head bolts at 5/8" so a 16mm spark plug socket fits perfectly and is usually 6 point so you can give it a bit more grunt. Cylinder 5 is on the left hand bank (as seen from the driver's seat) so you have less space than those of us with RHD cars as you have the brake modulator on that side. The hardest part will be getting the heat shield bolts. On a RHD, the rearmost exhaust manifold bolt causes everyone grief due to getting access so I suspect the same one on the other side might cause you problems. Easiest way of getting to it is to take the inner wheelarch liner out and go at it from through the wheelarch.

The heat shield bolts are crusty for sure. I started to remove them as i did a smoke test to make sure I did not have a manifold leak a few months ago. I ended up not removing it because a few bolts were not co-operating but I did not soak them or put heat in them so I think with a little more effort they will come out. Removing wheel arch is good to know and I just did that on the other side to put all new rear hard brake cables on so thats pretty easy and will give me better access. Also I did not even think about this properly, since its just cyl 5, can I just remove that side or will have have to remove left and right?
I have watched a few videos in preparation but will look at rave this weekend as well. It seems pretty straight forward like you said but with some swearing for bolts that don't want to come out. I wish I had my "garage" space already so i could get started on this already, or that the weather was nice. But I will keep watching stuff in preparation, also need to look into how to drop the sump.

Once the inlet manifold is off you are just looking at two very simple 4 cylinder pushrod engines sitting side by side. So you can ignore everything on the other side and leave it alone.

Start with removing that side. The ones on the other side are very likely to be in similar condition as the other three (1,3,7). Then you can decide if there is reason to continue on that side.

th.

Thank you everyone!