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Grand Touring - Engine Swap

Hi All,
I am based in the US and am considering putting in a used engine (since I have a blown head gasket) in my car which has a 2.5 liter engine. Got a number of questions that I'd welcome input on:
  1. Looking online I see that Mazda 3, Mazda 6 and CX-5 engines are listed as interchangeable. Are these truly identical or are there certain nuances that one needs to be aware of?
  2. Is there a list of other parts I should definitely replace (my car is at 90K miles) while engine is being swapped? I can certainly think of basics like spark plugs, new belts, water pump, etc, but wanted to see if there is a list of things that are recommended (thing that typically go bad when cars reach certain milestones). I am thinking it may make sense to address a number of things while the engine is out.
  3. The PCM on my car doe not have most recent software on it (per my dealer). Does it need to be flashed as par of the engine replacement job? If so, can any car mechanic do this as long as they have the right equipment?
  4. I read that on a newly built engine one needs to pay attention and reduce the risk of a dry start damaging a newly built engine by priming the oil system. Is that true, if so, how is it done?
  5. Finally, there is a bunch of used engines online offered by a number of companies. Some offer 2yr 3 yr warranties for extra $, some say the engines are inspected. Is there one or two reputable companies out there when it comes to buying a used engine? Are there any companies that sell re-manufactured engines for CX5?
Many thanks.
 

Chris_Top_Her

Banned
Moderator
Contributor
:
San Antonio, Texas
:
'15 CX-5 Miata AWD
Yes they all use the same engine (but it also depends on year). I recommend LKQ it will tell you based on your bin what is available and compatible. Their stuff is warranted and graded. It's unlikely to get a bad part from them. You don't need to flash the ecu, unless you have one of the CD engines then I would.
 
:
2019 CX-5 GTR
LKQ you say?

Corporate website:

one consumer site:

another consumer site:

another consumer site:
 
I got a quick update to share. My mechanic removed the head gasket (see attached photos below) and sent the cylinder head to his machine shop. What they found is a nice long crack on the external surface of the cylinder head (see attached photos). My mechanic also said that there were no overheating signs in the engine and that this may be a material defect failure. Does anyone have any experience with a similar situation? Could I just put in a remanufactured (not rebuilt) cylinder head and solve the problem? Or do you think there may be cracks on the cylinder block as well, and I am better off with a used engine (whose maintenance story will be unknown)? Once fixed I hope to sell the car (within the next 2 months), and I do not want to keep spending a ton of money on this. All input is welcome.
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Attachments

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg. Plano, TX
Contributor
:
Plano, Texas, USA
I got a quick update to share. My mechanic removed the head gasket (see attached photos below) and sent the cylinder head to his machine shop. What they found is a nice long crack on the external surface of the cylinder head (see attached photos). My mechanic also said that there were no overheating signs in the engine and that this may be a material defect failure. Does anyone have any experience with a similar situation? Could I just put in a remanufactured (not rebuilt) cylinder head and solve the problem? Or do you think there may be cracks on the cylinder block as well, and I am better off with a used engine (whose maintenance story will be unknown)? Once fixed I hope to sell the car (within the next 2 months), and I do not want to keep spending a ton of money on this. All input is welcome.
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Thanks for the update!

Since you’ve found the real issue, and plan to sell the car shortly, the best choice for you is to spend the least money putting the engine back. Used engine, rebuild head, whatever.

Have you figured out if it’s cheaper simply to get a used engine at the first place without trying to take the engine apart and find the culprit?
 
Thanks for the update!

Since you’ve found the real issue, and plan to sell the car shortly, the best choice for you is to spend the least money putting the engine back. Used engine, rebuild head, whatever.

Have you figured out if it’s cheaper simply to get a used engine at the first place without trying to take the engine apart and find the culprit?
Typically, it is less expensive to do an engine replacement, than going the route I went. However, I was able to do that since my mechanic was nice enough to deduct the hours spent so far from the total hours to do a full engine replacement.

I am interest to hear views around what gives the car more of a useful life. Is it just putting a cylinder head or an entire engine from another car? Also, any recommendations on what other parts need to be replaced while we are at it (I am asking this to get educated, not that I want to spend a lot more than I need to).

Thank you.
 
:
2014 & 2019 CX-5 Touring(s)
Given that the initial problem was a blown head gasket, I would think the best solution (and cheapest) is to put in a new/used head back in. I would further suggest you follow your mechanic's recommendation. He should be able to see if the block is OK.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg. Plano, TX
Contributor
:
Plano, Texas, USA
Typically, it is less expensive to do an engine replacement, than going the route I went. However, I was able to do that since my mechanic was nice enough to deduct the hours spent so far from the total hours to do a full engine replacement.

I am interest to hear views around what gives the car more of a useful life. Is it just putting a cylinder head or an entire engine from another car? Also, any recommendations on what other parts need to be replaced while we are at it (I am asking this to get educated, not that I want to spend a lot more than I need to).

Thank you.
Either way has benefits and drawbacks. It also depends on the skill of the mechanic. Nowadays an engine swap has less chance to screw things up, so it becomes a preferred way to handle the blown head gasket issue. Of course getting a brand new engine ( actually it’s always a rebuild) is expensive, a used engine has too many unknowns.

I don’t think there’re too many things need to be replaced at the same time in both situations. Engine oil、coolant、spark plugs、air filter、and any other maintenance parts. For a used engine, you can replace parts which is showing signs of oil leak, such as front and rear crankshaft main seals、front timing chain cover seals、oil pan seal、valve cover gasket、etc.
 
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