1947 rover

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digcot65
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1947 rover

Post by digcot65 » Mon Sep 27, 2021 9:29 am

Good morning as I said I have had to sell my Rover 12hp due to ill health.A friend has a 1947 Rover 12 which he asked me for help on .I found the number 3 cyl had no compression I checked every think as he said it has come on suddenly.In the end I poured some oil into the cyl to prove it was piston or valve,if the compression measured something ,it was the piston causing a problem and the oil was giving it some seal .Still zero .I had to leave him that day and I returned the following day and amazing,there was normal compression on the engine,I dont know if the oil had cleared a sticking valve,but the engine runs a treat.The car though immaculate is hardly used,which isnt a good thing ,but any answers from any member Len

Willem
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Re: 1947 rover

Post by Willem » Mon Sep 27, 2021 5:29 pm

I have in the past done a pressure test on a VW engine, rigged up a hose from the compressor to no.1 cylinder via the sparkplug hole, with both valves closed, gave it a bit of pressure and checked if there was any obvious leakage. air out of the radiator reservoir most likely culprit head gasket, engine breather blowing, leaking past the piston, air out of the exhaust, outlet valve, air out of the air filter inlet valve. Try all cylinders on turn and it should be clear where the problem lies
It sounds more complicated than it is, and I only used a few psi to check, 10 or so, in my case one of the outlet valves had carbon deposits on it. Whilst doing a compression test, I could see the pressure was down but the pressure test allowed me to narrow it down to the exact problem.
There are some good video's on youtube that show the process, I rigged it up with an old sparkplug (core removed) a bit of hose, a compressor connector and a couple of hose clips.
Will
Rover 12 Tourer, 1936
Range rover L322, 2009

TonyG
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Re: 1947 rover

Post by TonyG » Tue Sep 28, 2021 7:31 pm

Hi Len,

Well done on getting this one sorted, even if you don’t know exactly what the problem was. I think you are right in suspecting a stuck valve. If it was rings you would have had some compression but none suggests a valve. If the car is rarely used, it will sit with some valves open that could lead to one not closing fully when the engine is turned over. I’d suggest your friend runs the car more frequently to ensure everything keeps moving as it should. He was lucky to avoid taking the head off for a de-coke.

I’ve found that unleaded fuel burns very sooty when it gets old as it’s usually necessary to run the engine with more choke to compensate for the poor quality that results from the limited shelf life, causing the plugs to become very black. It may be that your friends car is running on old petrol and the valves are getting covered in carbon. Just a thought... Fresh petrol and take it out for a blast might be a good start.

Tony
Tony Gilbert

P1 12 Tourer
P2 12 6 Light Saloon
Discovery 3
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digcot65
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Re: 1947 rover

Post by digcot65 » Thu Sep 30, 2021 4:07 pm

Hello the car is immaculate,but in the 10 years he has owned it he has done 339 miles!!! He also has a Rover P4 which has just started to miss fire and blow smoke out .Supposed it will be my next job. So it shows standing doesnt help.I was surprised on the rocker box cover it says tappets 10 thou when warm .I thought it would have been less,the tappets are quite noisy on the car but check OK Len

TonyG
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Re: 1947 rover

Post by TonyG » Fri Oct 01, 2021 8:48 am

Len,

The earlier cars had a 5 thou tappet clearance, although this was often updated to 10 thou when the cam was changed. I believe the cam came with a red plate for the rocker box to replace the original. Your older 12 was probably 5 thou.

Tony
Tony Gilbert

P1 12 Tourer
P2 12 6 Light Saloon
Discovery 3
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digcot65
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Re: 1947 rover

Post by digcot65 » Wed Nov 17, 2021 4:52 pm

Hello the friend who I helped with his 1947 P2 went a run the other day and it was fine .However a couple of days later he tried to start the car and there was quite a noise. I had a look and 3 push rods are slightly bent and there is no compression on a couple of cylinders. I nearly have the head off but I didnt have a spanner with me to remove the two nuts on the front and rear corner of the head. Any idea what sizes spanner they are. I`m not sure,if a ring spanner will fit. Does any one know the position of each of the three timing wheels behind the timing cover.I feel the chain has jumped a cog or two So it made need a new chain and the wheels lining up my friend has the old workshop manual,but I cannot find the wheel positions Len

TonyG
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Re: 1947 rover

Post by TonyG » Thu Nov 18, 2021 9:17 am

Hi Len,

The head bolts are 5/16W and the timing chain cover bolts are 1/4W. I don’t know what the bottom pulley/ starting handle dog size is, but it’s big! There are only two sprockets; one on the crank and one on the cam. You need to get an up to date workshop manual to set up the valve timing with a new chain. It would have been a very worn chain to jump a tooth, but I doubt that has happened or all the push rods would be bent I should think! Had this been the case, the chain would have been very noisy beforehand. Before going down that rout, I’d suggest following the manual instructions to check the valve timing. You will need a dial gauge I expect. Been some years since I did mine and I cannot recall the details.

With any unexpected failure, I always wonder what, if any, work was recently undertaken. For example, had the tappers been recently adjusted, it’s possible that some were too tight resulting in the push rods bending over successive hot and cold cycles. It might take quite a while for the rods to bend.Or perhaps the head had been torqued down and the tappers not adjusted afterwards? Again, check the manual, but the head is only torqued to around 30ft/lbs and has to be re-torqued a while after, which is a faff as it’s not easy to get to all the bolts. The ones at the corners you mention, require one of those clever ring spanner torque reach attachments or simply done with a spanner- judged to be as tight as those torqued properly. There is a sequence to follow, as with all heads.

Hope that helps.

Tony.
Tony Gilbert

P1 12 Tourer
P2 12 6 Light Saloon
Discovery 3
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digcot65
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Re: 1947 rover

Post by digcot65 » Thu Nov 18, 2021 11:36 am

Thanks for the reply ,is it possible to see if the cam shaft and crank pulleys are in alignment there are usually marks on them .There were three pushrods that I could see and the thing is the owner went a run i the car a few days earlier and it was fine I can now get the head off and check it.I take it the two nuts at each corner of the head low down ,are the same 5/16whit. and will a ring spanner for on them as they looked close to the casting.This is the problem ,when you arnt in your own garage with all tools to hand Len

TonyG
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Re: 1947 rover

Post by TonyG » Thu Nov 18, 2021 3:16 pm

Len,

The Workshop Manual details setting up the valve timing when changing the chain or rebuilding etc. As such, checking the valve timing would be the same procedure.

Basically, turn engine in normal directing until the flywheel pointer is on the EP mark. At this point the No1 exhaust valve should be fully open. This is where a dial indicator is used, but you should be able to get a reasonable idea by rotating the engine back and forth around this point to ensure the valve is fully open.

There is no need to remove the timing chain cover or the cylinder head to undertake this check.

As I said, I doubt the chain has slipped a tooth and suspect there will be another reason that the push rods have bent.

Tony.
Tony Gilbert

P1 12 Tourer
P2 12 6 Light Saloon
Discovery 3
Discovery Sport

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luli
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Re: 1947 rover

Post by luli » Fri Nov 19, 2021 12:20 pm

The pulley socket size is 1-7/8.
To see a detailed description of the timing procedure have a look here: https://lulis.org/2014/05/13/%D7%A8%D7% ... %99%D7%93/
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
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