Shaking down my rebuild - a few issues...

[aspira]

I’ve been shaking down my RV8 3.5 for a while now, with a lot of support from everyone here - very grateful.

My testing trips get longer as I bed down the engine (about 100 miles on it so far), but I’m still plagued by problems as soon as I clock up a few miles on faster roads. Broke down today, so determined to get it running more reliably. As ever looking for some advice...

Main problem is the amount of smoke it’s now putting out. I had this problem previously and needed to have a new valve seat pressed in. Something had slipped down the spark plug hole and caused some damage to the piston and seat. Problem solved.

This seems to be a new problem (I think) which might be caused by a leaking heater valve, dripping coolant onto the v gasket and mixing with oil. I found a lot of coolant sitting on the gasket and could see it dripping from the heater valve. Although I’m not sure liquid can get past the gasket & rubber seals but I guess it wouldn't take much. I’m going to block off the heater valve, change the oil and see if that solves it. What do you think, is this plausible, or should I be looking elsewhere?

The second issue that worries me, but I don’t think is currently causing it to run badly, is the harmonic balancer. It wobbles a lot. The main shaft it's attached to seems ok, runs straight. Could this become a bigger issue and be putting strain on the crank, bearings or seals?

I've attached a few videos so you can see what’s happening.

Wobble on the harmonic balancer
https://1drv.ms/v/c/f2cf483bba82bf78/IQ ... w?e=JhE2WO

Smoking and balancer - engine running
https://1drv.ms/v/c/f2cf483bba82bf78/IQ ... 4?e=JoIUNg

Any help and advice, much appreciated.

[scudderfish]

That belt looks very loose, it slips when you rev the engine. Is your crank bolt done up f*cking tight?

[scudderfish]

For reference, this is what I needed to undo mine to give an idea of how tight it should be

[aspira]

Yeh - it's a beast I know. I guess it might be too loose. It's been so long since I finished that part of the build. I'll definetly try to retighten it. I know they can slip on the key sometimes. That could be a fairly simple fix - but I might regret saying that when I'm dangling from a breaker bar.

Yes the belt's too loose, just noticed that when I shot the video.

Thank you...

[aspira]

On reflection I don't think the smoke looks like coolant. It's grey and blue. It's probably passing through the valves.
I'm assumming a leakdown test would be the best way to be more certain.
Does anyone know where I can get a leakdown test done near North London?
I don't have access to air.

Many thanks

[Ian Anderson]

Do your valve cover breathers go to a port on the carb?
If so is it the full vacuum port that will suck everything through it and then feed into the cylinders? (Brake booster port?

The breathers normally run to the underside of the air filter housing so not trying to draw a huge vacuum

[aspira]

Hi - I’ve got one side that has an inline non return valve and goes into the carb port. The other side users a small filter on top of the rocker cover. Eventually I was going to remove the filter and run that into the carb as well.

It’s using the port on the Edelbroke for this, the brake and gearbox ports are different.

Is this wrong ? And could be the cause of the smoking?

[Ian Anderson]

Take the hose off the carb and block it / clamp it then try to see if it is still smoking!

Basically remove the vacuum.

Best to put the end of the hose in a plastic bottle and collect anything that comes out as it may still throw out oil. You should can also feel any draft coming out as this will be blow by probably rings still bedding.

That would be my checking route

Ian

[FBW]

That seems like a lot for blow-by.
Is there perhaps too much oil in the oil pan?

greeting
Frank

[aspira]

Thank you everyone.

I removed the PCV from the equation & let the pipes vent to air. Didn't solve the problem - still lots of smoke.

I did check the oil level. It's on the line of the high mark, so probably overfilled slightly. I think it should be between the marks, although there's some question about the stick and sump - I don't think I bought them together and i can't remember what quantity of oil I put in originally. Would overfilling be a cause of the smoke?

I did a quick check for the valve guides. Ran the car down a hill on overun, no throttle, then put the throttle down at the bottom and checked back for a big puff of smoke.
There was, so I'm guessing a problem with the valve guides.

Maybe the new seat wasn't in line with the valve guide the valve guide wasn't checked for alignment damage.

I did do a compression test. #1 is down 25% so I think this all points to the original problem not being fixed properly. I'll pull off the head and take it back to the shop.

I'll try and tighten the balancer or check it's at about 150lbs. If not I'm hoping it's simply repalcing the balancer not the crank. I can't think of anyway to check a balancer and most of them are pretty old and the rubber is rock hard. Is there an alternative? Mine came off a P6 with the V slot already cut into the pully.

I'll update once completed - help make the thread useful for others... Thanks again - Stephen

[scudderfish]

I'll update once completed - help make the thread useful for others... Thanks again - Stephen

Thanks, that's what makes this forum a gold mine of information.


https://xkcd.com/979/