Jump to content
Sign in to follow this  
Riceburner

Blown welsh plug

Recommended Posts

I asked this question in my build thread but is probably more suitable in this section. First time at the track yesterday did 1 warm up lap and almost 1 flying lap when a coolant smell wafted into the cabin, I also spun in my own fluid. Got back to pits to find a welsh plug completely missing from the front of the block on the drivers side! Is there a reason it would pop/blow out?

 

Temps were fine, oil pressure fine. I used permatex no.3 (aviation cement) when installing them.

 

I was able to repair, test and drive home and the water level has not dropped since topping up. I'd like to get to the bottom of it as I think I was very lucky not to destroy my brand new motor :'(

 

Anyone else had this before? Are the low temp stat, LD28 water pump, Kameari high pressure cap a bad combo at high revs?

Share this post


Link to post
Share on other sites

Good point about the water pump mod you did.

Maybe not necessary and not suited to high RPM's?

 

Why do you have a low temp thermostat?

How high pressure is the rad cap?

 

Also, maybe you just got an under toleranced welsh plug? How did it go in? any different to the others (easier)?

Share this post


Link to post
Share on other sites

Cap is 17psi instead of 12.8psi standard. I ran all this stuff on the old engine except the pump without any issues for 2yrs, I run the low temp stat just so it opened earlier on track. It's the first plug closest to the timing cover which I believe is the exit of the pump to the block. They were fairly tight fit, used large socket and mash hammer to fit them.

 

Maybe an underdriven water pump pulley is required? From what I've read bob sharp used the LD pumps but with a restrictor instead of a stat, could the pump/stat be over pressurizing the block at sustained high revs? I shifted at 7,000 in all gears. Would an underdriven water pump cause overheating issues on the street?

Share this post


Link to post
Share on other sites

One thing I have done with my new motor, is get an under-driven crank pulley; if you will be revving a fair bit then might be a good idea to spin the alt and water pump a tad slower. Don't think they were designed with 6500+ rpms in mind...specialy diesel components.

Share this post


Link to post
Share on other sites

Dimitri where did you get it from, would i be able to adapt the BMW balancer onto it? Will it cause overheating issues on the street?

 

I was in the pits next to your boss yesterday, he had a wicked little Renault.

Share this post


Link to post
Share on other sites

Its a copy of a Nismo balancer; bought it from Daniel (dazzed). Not sure if he can get any more? It's not on the car now and I do have a heating issue but I think that my cooling fan is to blame. A standard balancer is on the front of my L24 at the moment. With the underdriven one, I never had a cooling issue. I'm hoping to have it all together for the Island so we will see!

Share this post


Link to post
Share on other sites

I removed several balancers off L28's I wrecked and they were all different diameters?

 

What diameter is yours Dimitri and Gareth?

Share this post


Link to post
Share on other sites

My brother has just finished building an LJ Torana for Group Nc. First test day at Winton it spat a welsh plug on his second lap. He replaced it at the track and its been fine since.

 

Welsh plugs can vary in fit and depend on how they are installed as well.

Share this post


Link to post
Share on other sites

Just measured my pulley, in the "V" is approx 80mm and at the top is 100mm. Outer overall diameter of the balancer is about 150ish I think...maybe bigger.

Share this post


Link to post
Share on other sites

Hmmmm, I wonder who could copy it?

I'll have a look at it if you wanted.

Wasn't there a post about rebonding the balancers?

Could turn up the parts, then send them there.

Share this post


Link to post
Share on other sites

Ha, I have a guy in mordialloc who has done all my brake work really cheap but if your offering Simon. Thanks, david + peter that makes me feel a bit better about it. I had a really good look at the track on sunday and it all looked ok, the hole was very clean. Bit off topic but I also saw a Kameari balancer for about $380, The ATI balancer is out of my budget at the moment. I might just see how it goes with the current setup for the time being, and I'll make sure I have welsh plugs in my spares bag......

post-1489-14402362086_thumb.jpg

Share this post


Link to post
Share on other sites

I'll post up the video later today, but Harry (my boss) had his video recording camera watching you from behind and about 150 meters before the right hand where you spun, you can see a puff of steam/smoke blow out from the drivers side then you going around the turn and losing it..

Share this post


Link to post
Share on other sites

Ha, I have a guy in mordialloc who has done all my brake work really cheap but if your offering Simon. Thanks, david + peter that makes me feel a bit better about it. I had a really good look at the track on sunday and it all looked ok, the hole was very clean. Bit off topic but I also saw a Kameari balancer for about $380, The ATI balancer is out of my budget at the moment. I might just see how it goes with the current setup for the time being, and I'll make sure I have welsh plugs in my spares bag......

 

Gareth the ATI balancer isn't that much more, I just bought one, it was about $490 posted

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×