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Does anyone have a recommended place to rebuild cylinder heads. After 375 hours I have two front cylinders that wont make compression, both are 46/80. I can hear the air through the exhaust and intake valves. The rear cylinders are both 70+/80. I am waiting on new heads from Sonex but would like to repair the original heads for spares. I don't have the tooling or skill to do the job myself so I'm wondering who you might have used and about how much it will cost to replace the valves,guides and seats.

My original heads are sitting in my hangar for the same purpose Bill. I wish I knew a national reputable shop that I could recommend for you, but I don't. My plan is to use a local auto repair shop, hopefully one that specializes in VW repair.

Is there a local auto engine repair shop in Peoria that knows about VW's?

Try RIMCO, thats were Steve from Great Planes used to send all his stuff

Might be worth trying Mofoco -- where Sonex gets their current cylinder heads. Mofoco rebuilt their own heads and might rebuild a 3rd party head. From what I understand they do all kind of work on VW engines, generally. I think they quote $150 in labor plus parts for a head rebuilt (I don't recall if it is for one head or for a pair).

wlarson861 wrote:Does anyone have a recommended place to rebuild cylinder heads. After 375 hours I have two front cylinders that wont make compression, both are 46/80. I can hear the air through the exhaust and intake valves. The rear cylinders are both 70+/80. I am waiting on new heads from Sonex but would like to repair the original heads for spares. I don't have the tooling or skill to do the job myself so I'm wondering who you might have used and about how much it will cost to replace the valves,guides and seats.

If they are not making compression then there is an issue with the valves. Buy new valves and valve guides (make sure you get the right sizes and type). Any local machine shop can clean up the valve seats and install the new valves. This is very simple stuff for an engine machine shop and doesn't take a VW specialty shop. I did it last year and everything was tight again. I think I paid $150 for the labor and it was done in a couple of days.

Thanks for all the replies. I may contact Mofoco and get a quote(they are close) or do as suggested and order the parts and get the locals to do the work. Since posting I was tipped off of a local VW shop that I may try. If the price is good and the work is satisfactory, I will let the group know.
Thanks again all.

You may not want to emphasize to the workshop (or mofoco) that it is going to be used on an aircraft engine. They may not want to know that. They might have reservations working on a part used in an aircraft due to liability concerns.

Quick question - How are you checking the compression? The way you perform the check can give you wildly different readings! Here are a couple of articles/videos to check out, from respected A&P Mike Bush:

http://eaavideo.org/video.aspx?v=2149054014001
(Compression is discussed in the beginning, and again in detail from about the 18-minute mark)

http://www.avweb.com/news/savvyaviator/188758-1.html

Enjoy,

--Noel

Is my math right to rebuild or buy? $150 in labor + $40 in valves + $20 in valve guides + $10 shipping = $220 rebuild vs. $325 new + shipping. Not sure rebuilding is worth it for me. Have new back ordered from Sonex, maybe fix the old one to have spares ( or hanger art?).

Pulled the 3&4 head after 3 failed compression test. Valves were tight in the guides, valve seat concave, scoring on the exhaust valve stem. I think they would look good if I'd bore-scoped them. Here's some pics.
https://drive.google.com/open?id=1_jfM9 ... R7qNgb59fn

Gonna pull the other head and see if that one is wearing out prematurely also. Only 150 hours :(

Just put on new ones. The pictures show cracks in the head between the valve seats.
The valve seat concave shape is definitely not good. Big chance the other head has the same problem.

You can rebuild the old ones and keep them as spares. It saves you $200 on the next head change.