Diesel Engine Valve Seals

As far as which ones need seals you will need to check with the manufacture. It will depend on the valve guide used. The seal is to keep the excessive oil from running down the valve into the engine cylinder and burning. Also to wipe the valve stem clean as it is moving into the guide.

Thank you,

I'll put it different. The seals I have. Just don't know for a 4 cylinder with 2 valves per cylinder, if I need to put 4 (this was the configuration) or 8, like the supplier has send.

How was the engine built from the manufacturer? They are the experts on that engine. But, if you are willing to share some info on the engine, I would be willing to look up what replacement parts are listed for it.

Thanks for the information.

I include 2 pictures of the head that has been removed. In the front you will see that there are 5 ports. The middle and the two on the outside are the exhausts.

On this head (I hope it shows on the pictures) valves 2,3,6,7 are the intake valves. They have the rubber caps on it. The other valves (exhausts) don't.

I have put a replacement head on this engine configured the same way, but I notice some blue smoke out of the exhaust. Not really plenty, but too much.

The engine has been sitting here for over 2 years and the diesel is probably somewhat contaminated with algae. I try to find out what is the cause of the smoke and want to remedy it.

The engine is a British BL1800 cc diesel from 1975. The manufacturer has gone bankrupt some 25 years ago, however new parts are still supplied since the engine has been used in Toyota land cruisers and Sherpa vans in India. (still in production I've been told)

I bought the so called head job decarb kit: all gaskets for the top, heat washers and seal washers for the CAV injectors, thermostat seal etc..

This kit has 8 rubber caps in it while the old head had only 4 installed in the intake valve stems. All the kits have eight rubbers.

Is it common to also place these over the exhaust valves? What is the function here?

Where else can the smoke come from and what is your advice. Thank you.

The added heat from the exhaust valves may have caused the valve seals to harden, crack and fall out. My suggestion is to install them and see how it goes from there.

When valve stem seals leak, there will usually be oil smoke when starting, or when a gasoline engine is used for braking. Other times the seals leak so slow that smoke is not noticeable. But in your case, with no seals at all on the exhaust, smoke may be more prevalent. Can you examine the exhaust ports without major dismanteling? If the oil is from the exhaust seals, the ports should be oily. Good luck.

Every Engine I have rebuilt had seals on every valve.

To Bob C and OZZB:

The engine has run about 10 hours now and it is about time to re-tighten the head bolts.

I think I will put caps on the exhaust valves too and as you say: see what happens. Maybe in those days they didn't care too much about some smoke? Or the former mechanic might have run out of seals? They have been "fixing" this engine with what they found I guess, and that was not much. Need to make some tools again to deal with springs and valves. Did any of you perform this with the compressed air in the cylinder to keep the valves in place, preferably at TDP? I'd like to take the glow plug out to connect the air to the cylinders.

I have never had to do it on a diesel. But on a gasoline engine, the compressed air will drive the piston to the bottom. Good luck.

Use a breaker bar and socket on the crankshaft damper/pulley nut and chain/tie down the breaker bar to resist rotation. You don't need much air pressure to keep the valves seated - 10 to 15 psi should be enough. That should stop the engine from rotating while you change the seals on the valve stems. Obviously each cylinder will have to be rotated to TDC on compression stroke and then lashed down to install the valve stem seals for that cylinder.

Never work on diesels but used compressed air all the time to hold the valves closed on gas engines. Don't take much pressure. Usually not enough to rotate the cylinder. Even if it does its not going far. Just keep you hands out the way when you apply the pressure. We used an old spark plug with the ceramics broken out and tapped 1/4" NPT for air line quick disconnect. You maybe able to do the same with a glow plug if you can't find one they do make them for the application.

Did you ever use rope? Just feed rope into the spark plug hole while the piston is down. Then rotate the crank till the rope jams up against the head and valves. Now you can remove the valve springs without loosing the valves, and with no air.

I've never heard or tried that trick keep in mind the next time when air is not available. Most of what was done was shop work. Had spark plugs rigged up to fit most engines.

On the duel plug heads, do I need twice as much rope?

Use valve stem seals on both intake and exhaust valves. As the valve guides wear and the clearance between the guides and the valve stems increases, enegine vacuum can suck oil into the cylinders. The stem seals are intended to prevent this, but they can become hardened by exposure to heat and oil, crack, or take a set and no longer seal effectively after a while. This is quite obvious with gasoline engines that sit idling at traffic lights and then billow blue smoke when they accelerate after the light changes. They suck in oil while idling and then burn it when the throttle is opened. Diesels don't show it as much because their fuel is basically a form of oil that is ignited through compression so the oil doesn't accumulate in the combustion chamber at idle but is burned continuously along with the diesel fuel. I would expect extra smoke only if the valve guides are seriously worn and the valve stem seals are really leaking creating a fuel rich condition. In that case new valve stem seals will help for a while but the guides really need servicing/replacing.

Hello. As already explained the rubber like (not always rubber ) valve seals are a barrier to lubricating oil entering the combustion chamber.If the exhaust valves had valve seals installed before your work, you will find the pieces in the oil pan. Personally i make a practice to inspect the old valve seals for missing pieces or in your case maybe missing altogether by removing the oil pan and oil pump screen.It is possible for these missing pieces to enter the oil pump and cause it to seize. Hope this helps.

On a few Fors motors I have seen the remnants of valve stem seals get sucked into the oil pump and sheered the roll pin on the distributer gear. The good news was that the engine stopped running.

I still find it strange: the head I removed had only rubber cap seals on the intake valves.

I showed a picture of the head and I do not understand the oil distribution there too well. As I thought the oil is supplied by the rocker shaft and rockers from the oil pump and then drained to lower parts again. Please explain me what I am missing.

The new head I ordered complete with valve and springs in place and got delivered with also the rubbers on the intakes. The first (removed) head is probably 30 years old and the rubbers on the intakes are still consistent rubber. Exploring the oil pan is not easy since the engine sits in the bilge, close to the floor. Most bolts are out of reach.

The oil is to be removed with a pump.

Is there a chance that they do not put rubbers on the exhaust on purpose? Maybe a heat problem if no oil can get between stem and bushing? Is the valve not cooled by the pipe?

I made the tools to remove the springs, but the job is bigger as thought before: the rocker stands also house the head bolts and I need to remove the rockers to get to the stems.

I also installed a new raw water pump, with plenty more capacity. It is incredible what comes out of the wet exhaust now. Plenty of salt, organic dust and dirt.

Probably I will need to bypass the pump. It is a Jabsco but I had to bring it from 1/2" to 3/4" because the oldie became obsolete. (and is now sold for $1.000.00 plus) and doesn't last long before it leaks. I have a whole collection here.

Strange is that the engine smokes, but not with a predictable pattern. The start is always smokey, but sometimes I have no smoke at all when running and suddenly it starts smoking.

The engine ran 25 hours now and the head has to be tightened again. The books says to loosen the bolts 1/6 of a turn and then 10,5 kgm following the sequence.

Will taking off the rocker stands need a new gasket or can I use the old one?

Thanks

Try asking the person that you paid good money to why the gasket company sent 8 seals, and the head he sold came with only 4.

Try asking the company that you paid good money to why they sent 8 seals when the head came with only 4.

These people have profited by your hard work, and have an obligation to answer your questions.

I followed your reasoning:

Answer: The seal kit - strange - is that of a cummins diesel and has been composed by them. They could not tell me if Cummins bought the BL design or production rights.

They are not 100% interchangeable. So is there a gasket for the timing cover - originally it had none installed - and I have put it, but the crankshaft pulley caused everything to stop rotating - needed to make a 2 mm washer to get clearance again.

I did work on many diesel before, mainly Mercedes, but this one is like a fixer upper. Note: today only a little bit of smoke at the start - mainly because it doesn't crank easy after sitting too long - I lose pressure in the diesel supply. (next project). Thanks.

Grandpaw, thank you a lot. This comment is so complete, that I will use it as a guide for further troubleshooting. This engine is by now an oldtimer and so are the people, who worked on it. The Toyota first landcruisers are also 40 years old now. The manual I have now doesn't help me a lot. I have to rely on parts that are manufactured in India and the engine has gone through a lot of changes meanwhile. Their distributor for Europe is in Turkey and he supplied the new ready assembled head and the rocker assy, which was assembled wrong.

The cylinders are in perfect shape with no "ridges" at the top or bottom of the sleeves. The gasket package comes in a set and in there are 8 rubbers. They are after market.

I appreciated your time and the expertise of your answers. D.