Hello first post - Shaking down my rebuild - a few issues...

[Stephen Thomas]

Hello everyone - my first post!
Found you all from a recomendation on the V8 Owners Forum in the UK and hoped I could ask your advice about some engine problems I'm having - alongside friends on the UK forum.

I built a Rover RV8 3.5 (From a 1981 Disco) from the ground up, to go into my 1978 MGB. It runs an Edelbroke 1404 and a Mazda MX5 5 speed gearbox.

I've been shaking down the RV8 for a while now, with a lot of support from the UK V8 forum.

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.

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. - Not something I could fix. It went to the machine shop, problem solved and has been running nicley for several weeks.

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 is 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://tinyurl.com/MGB-V8-UK-1

Smoking and balancer - engine running
https://tinyurl.com/MGB-V8-UK-2

Any help and advice, much appreciated.

[BlownMGB-V8]

Don't put off replacing the balancer, it can take out your radiator.

The smoke could be a PCV problem, very likely with switching to a 4bbl carb. There are several good threads here about that but basically  adopt the US system.

Jim

[Al Moor]

You should definitely get the harmonic balancer sorted.  If nothing else, it will eat belts regularly.  As for the smoke, is it only under vacuum?  The video shows it smoking at idle, but does it smoke under acceleration?  Does it smoke more when you first start the engine, or is it fairly constant?  I'm no expert on the Rover motors, but generally it's either sucking oil past the valves or from an intake gasket.  Less common, especially since it's a new build, is that it's pushing oil past the rings, or the rings haven't seated yet.  If you let the PCV vent to air, does the smoke stop?  Is your PCV hose wet with oil on the inside?

Lots of demons to chase.

Welcome to the group and best of luck!

[MGBV8]

Replace that harmonic balancer.

What oil are you using?  Did you use a break-in oil, or still using it?  What procedure are using to bed in the piston rings?

I would be using a conventional dino motor oil with low or no detergents for 500-1000 miles.

[Stephen Thomas]

Thanks for all the helpful advice and useful pointers.

The harmonic balancer has become worse I think. I do wonder if it's moved on the key or just wasn't tight enough. Anyway, that has to be sorted, one way or the other.

On reflection my thoughts about coolant were wrong. The smoke is grey and blue and the valley gasket is well sealed. The MG heater valve isn't any good - even when it doesn't leak. I'll remove it and block it off for now.

On oils Valvoline V1 20:50 - I didn't use a breaking in oil. I broke the Cam in with 4-5 power runs at 4500rpm....and very little idle. I didn't follow any particular proceedure with the rings, apart from very light driving. A few errors here...!

I did spend a lot of time with the engine idling - no smoke initially. Probably shouldn't have done that, it could have glazed the cyclinder bores which might allow oil to get past the rings.

I'm going to check the PCV first and vent it to air - see if that does anything, although the smoke does appear on acceleration and idle. Less smoke at first when cold.
I'll also check compression on all cylinders - see if that reveals any clues. And I'll look at the intake gasket - spray some carb cleaner arond the Edelbroke base. Easiest stuff first.

It's done about 100 miles, so maybe I should do an oil change as well see if that helps.

It's probably worth doing a leakdown test before going any further. Maybe that will reveal further clues. Not easy without shop air, but I'll give it a go.

Lastly I'll pull both heads off and investigate. Is it worth filling the bores with parafin and leaving overnight to rule out the bores and rings?

I'll report back on anything I find. London is in the middle of a crazy heatwave (38ºC today - 100.4°F in yr world) so might take a while.

Thanks again for helping me pull together a rough plan.

[BlownMGB-V8]

Don't think I'd bother with the parafin, it'll leak past the ring gaps regardless. But the compression and leak down tests are a good idea.

The rubber ring in the balancer fails eventually just from age.

This link:
https://www.britishv8.org/smf20/index.php?action=search2

Should answer most pcv related questions I would expect.

Jim

[MGBV8]

I break in cams by immediately raising rpm to 2500 for 20 minutes.  Some vary it between 2000 & 2500 rpm. After that, I change the oil & filter.

[Stephen Thomas]

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