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Rear Crank Seal - Replace With Engine In Place?

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Perdido Avatar
Perdido Gold Member Rut Rutledge
Tuscaloosa, Alabama, USA   USA
Shaun,
Once you get you engine plumbed correctly, remove the oil filler cap and place a piece of plastic wrap over the opening. With the engine running the plastic wrap should suck in slightly, if it blows out you either have it plumbed wrong, a hose is stopped up, or you have excessive blow by.
Good luck, Rut

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ric350 Avatar
ric350 Jim Feeney
Holmdel, NJ, USA   USA
Shaun,

When I got my Tr4a, the PO had removed the stock Tr4a PCV system, and installed the Tr4 style breather tube to the block (down by the fuel pump). It also had a "radiator cap" style oil filler cap (non-vented), so the PO installed a small aftermarket breather/filter to the valve cover tube. With this configuration, I never had any oil blowby issues. Recently, I replaced the oil filler cap with the stock Tr4a breather cap (which you appear to have), and plugged the valve cover tube. Still no problems with blowby. So maybe using the Tr4 block breather tube is the way to go. Unfortunately it is my understanding that removing the Tr4a block plug for the tube is difficult with the engine in the car.

Jim

Dan B Dan Blackwood
South Charleston, WV, USA   USA
Hang a bottle somewhere low, maybe down by the starter or maybe even better would be by the fuel pump and run the draft tube that you replace all that stuff with into the bottle. You will have a catch for any oil that comes out the breather, and you can pour it back in to the engine instead of rustproofing your frame. I have a friend with an AH100/6 who does it that way.

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TriumphantMan Avatar
TriumphantMan Raymond C
Southeast, Southeast, USA   USA
For the crank seal, I used the Roadster Factory's HP600 kit: Oil Seal,includes Viton Seal, modified1229.00229.00seal casting, and centering tool. It has worked very well with no leaks. I did soak the gasket in permatex overnight and it does make a mess. So, I'd rather have a permatex mess than an ongoing oil mess.


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smdl Gold Member Shaun Laughy
Courtenay, BC, Canada   CAN
In reply to # 1494157 by Geko Based on your pic, I bet this engine isn't vented at all. First thing to do is removing the plug on the rocker cover and replace it with a draft tube open to atmosphere. Your oil leaks will drop dramatically.

Hi, folks.

Sorry for the delay in replying -- it's been a busy week!

Okay, will try opening up the valve cover outlet, and will report back.

I mentioned above that the non-standard PCV filter was connected to a steel pipe that runs behind the head. I took a look at that tube on the driver's side earlier today, and found that is runs down the side of the block, and into a port near the bottom (see pics).

When looking at the PCV system, I can see and understand the upper plumbing that comes out of the valve cover, through the one-way PCV valve, and into the intake manifold. However, what I'm not sure about is this steel tube that comes out of the lower block on the driver's side, and wraps around behind the engine. Where is this supposed to go on a stock TR4A?

Thanks for all your help!

Cheers,
Shaun


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smdl Gold Member Shaun Laughy
Courtenay, BC, Canada   CAN
In reply to # 1494165 by Perdido Shaun,
Once you get you engine plumbed correctly, remove the oil filler cap and place a piece of plastic wrap over the opening. With the engine running the plastic wrap should suck in slightly, if it blows out you either have it plumbed wrong, a hose is stopped up, or you have excessive blow by.
Good luck, Rut

Thanks, Rut. I assume what you describe is due to there being slight vacuum from the connection to the intake manifold, correct?

Cheers,
Shaun

smdl Gold Member Shaun Laughy
Courtenay, BC, Canada   CAN
In reply to # 1494169 by ric350 Shaun,

When I got my Tr4a, the PO had removed the stock Tr4a PCV system, and installed the Tr4 style breather tube to the block (down by the fuel pump). It also had a "radiator cap" style oil filler cap (non-vented), so the PO installed a small aftermarket breather/filter to the valve cover tube. With this configuration, I never had any oil blowby issues. Recently, I replaced the oil filler cap with the stock Tr4a breather cap (which you appear to have), and plugged the valve cover tube. Still no problems with blowby. So maybe using the Tr4 block breather tube is the way to go. Unfortunately it is my understanding that removing the Tr4a block plug for the tube is difficult with the engine in the car.

Jim

Thanks, Jim. I kind of think that this is almost what I have now. It would seem that the pipe coming out of the port on the block currently goes up and behind the engine, not down like the original road draft tube, but it is still open to the atmosphere (only has that non-standard filter on it). It seems to me that this should be venting any crankcase pressure, correct?

Cheers,
Shaun

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smdl Gold Member Shaun Laughy
Courtenay, BC, Canada   CAN
In reply to # 1494419 by Dan B Hang a bottle somewhere low, maybe down by the starter or maybe even better would be by the fuel pump and run the draft tube that you replace all that stuff with into the bottle. You will have a catch for any oil that comes out the breather, and you can pour it back in to the engine instead of rustproofing your frame. I have a friend with an AH100/6 who does it that way.

Good idea!

smdl Gold Member Shaun Laughy
Courtenay, BC, Canada   CAN
In reply to # 1494439 by TriumphantMan For the crank seal, I used the Roadster Factory's HP600 kit: Oil Seal,includes Viton Seal, modified1229.00229.00seal casting, and centering tool. It has worked very well with no leaks. I did soak the gasket in permatex overnight and it does make a mess. So, I'd rather have a permatex mess than an ongoing oil mess.

Thanks, Raymond. That's the exact seal kit that I have. Thanks for the great pictures!

Shaun

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ric350 Avatar
ric350 Jim Feeney
Holmdel, NJ, USA   USA
Shaun,

Since you have the stock Tr4a PCV system (valve cover to intake manifold plumbing, plus the breather oil filler cap), then that should have taken care of any vapor pressure per the Tr4a design. However, as some PO went through the trouble of removing the block plug, and added that steel breather pipe, then a blowby condition must have existed with the stock setup. Perhaps there is a problem with the one-way valve in the PVC system? I would try Ruts' idea of using the plastic film, but put it on the outlet side of the PCV valve (intake manifold side), and see if there's any venting taking place through the PCV system.

Jim

smdl Gold Member Shaun Laughy
Courtenay, BC, Canada   CAN
In reply to # 1495802 by ric350 Shaun,

Since you have the stock Tr4a PCV system (valve cover to intake manifold plumbing, plus the breather oil filler cap), then that should have taken care of any vapor pressure per the Tr4a design. However, as some PO went through the trouble of removing the block plug, and added that steel breather pipe, then a blowby condition must have existed with the stock setup. Perhaps there is a problem with the one-way valve in the PVC system? I would try Ruts' idea of using the plastic film, but put it on the outlet side of the PCV valve (intake manifold side), and see if there's any venting taking place through the PCV system.

Jim

Hi, Jim.

Unfortunately, I don't have the original PCV setup. That has been removed on the car as it sits, and I have checked the parts stash that came with the car, but came up empty. So, as it sits, the PCV ports on the valve cover and manifold are plugged, and a long steel tube/rubber hose combination has been plumbed into what I suppose must be port where the old road draft tube would have been. In addition, the regular TR4A-style oil filler cap (with the small foam filter in the top) is in place. I'm going to try the plastic film trick today.

Based upon what I have learned so far, here are the questions that I'm hoping others might be able to offer opinions on:

1. Based upon my pictures above, can someone validate if the tube I have pointed out is indeed exiting from the port where the road draft tube on the TR4 would have been?
2. This tube really looks like a factory piece as it closely follows the side of the block up, curves to the rear, and passes behind the engine to the passenger's side. Is there any chance this is some sort of original piece, or is this port on the block always plugged on TR4As? Was there ever a fitting like this on any of the TR 4 cylinder engines?
3. Assuming that the lower crank case is indeed properly vented through that metal tube that comes up on the driver's side, and goes behind the engine, should the engine not have sufficient breathing now? On the earlier road draft cars, was ventilation needed at the top of the engine as well? Would the current TR4A vented oil filler be considered sufficient on those cars that came with a road draft tube? I see that the TR4 used a different style of oil filler cap.

I am still planning to remove the engine, check it over, and add the Mad Marx Viton seal, but I really would like to completely explore any potential breathing issues first.

Thanks for all your help, folks. I'm new to these engines and while I'm starting to build some understanding, nothing beats the incredible combined experience here!

Cheers,
Shaun

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
1. Yes, that's the port in the block. However, the tube is much smaller diameter than the original road draft, and looks to be longer (hence more resistance to air flow).

2. I do not believe that is a Triumph part. AFAIK, TR4 went directly from having the road draft, to having the hole in the block sealed off (tho there were several variations in other places).

3. Even the stock road draft tube allows some pressure build up; if the rings are a bit worn. I have the stock setup on my TR3, with moderate ring wear, and it still blows air/combustion gases out the vented fill cap under some circumstances.

As a side comment, it's my belief that the original TR4A setup with the PCV valve was also not sufficient under some circumstances. It relies on there being enough intake manifold vacuum to suck all of the blow-by flow through that relatively small orifice in the PCV valve. But, with the throttle wide open (one of my favorite operating conditions smiling smiley ), which results in maximum blow-by past the rings; there is essentially no manifold vacuum at all!

American PCV systems allow for this case by using a rather large diameter, short fresh air intake and allowing the blow-by to flow backwards through the intake when the PCV can't flow enough. Triumph seems to have overlooked this feature.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

smdl Gold Member Shaun Laughy
Courtenay, BC, Canada   CAN
In reply to # 1495890 by TR3driver 1. Yes, that's the port in the block. However, the tube is much smaller diameter than the original road draft, and looks to be longer (hence more resistance to air flow).

2. I do not believe that is a Triumph part. AFAIK, TR4 went directly from having the road draft, to having the hole in the block sealed off (tho there were several variations in other places).

3. Even the stock road draft tube allows some pressure build up; if the rings are a bit worn. I have the stock setup on my TR3, with moderate ring wear, and it still blows air/combustion gases out the vented fill cap under some circumstances.

As a side comment, it's my belief that the original TR4A setup with the PCV valve was also not sufficient under some circumstances. It relies on there being enough intake manifold vacuum to suck all of the blow-by flow through that relatively small orifice in the PCV valve. But, with the throttle wide open (one of my favorite operating conditions smiling smiley ), which results in maximum blow-by past the rings; there is essentially no manifold vacuum at all!

American PCV systems allow for this case by using a rather large diameter, short fresh air intake and allowing the blow-by to flow backwards through the intake when the PCV can't flow enough. Triumph seems to have overlooked this feature.

Cheers, Randall. Very helpful, and good point about vacuum being absent when blow-by is likely to be highest.

I was able to conduct the plastic film test yesterday, and can confirm that there was clearly positive pressure in the engine, even at idle. Honestly, given that there is no vacuum connection present, I can't see that the reverse could have been true, but it was a good visual exercise anyway.

So, based upon input and tests so far, here is my plan:

  • Find an original road draft tube and install that (likely with a hose and catch can). Makes total sense as the port on the block is already open.
  • Add an early vented oil-filler cap to improve breathing at the top end.
  • Pull the engine to install the Mad Marx rear seal, and check pistons/rings/liners/bearing clearances while I am in there. Replace/rebuild as necessary.

Anything else I should be doing or considering? Anyone have a spare road draft tube they would part with?

Thanks again, everyone.

Shaun

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
I'm sure Marv does. If not, let me know and I'll dig one up.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

smdl Gold Member Shaun Laughy
Courtenay, BC, Canada   CAN
Thanks, Randall. Will check with Marv to see what he has. Will also check at a more local locale. smiling smiley

Cheers,
Shaun

PS: It might take some time to get all of this done, but I will make a point of coming back and updating my findings once complete.

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